diskutil

Disk utilities - Format, Verify, Repair (local disks.) This includes options not available in the Disk utility GUI.

Syntax
      diskutil [quiet] verb [options]

VERBS

Each verb is listed below with its description and individual arguments.

     list [-plist] [internal | external] [physical | virtual] [device]

List disks, including internal and external disks, whole disks and partitions, and various kinds of virtual or offline disks.

If no argument is given, then all whole disks and their partitions are listed.

You can limit the number of disks shown by specifying filtering arguments such as internal above, and/or a device disk. When limiting by a disk, you can specify either a whole disk, e.g. disk0, or any of its slices, e.g. disk0s3, but filtering is only done at the whole disk level (disk0s3 is a synonym for disk0 in this case).

If -plist is specified, then a property list will be emitted instead of the normal user-readable output.

A script could interpret the results of diskutil list -plist and use diskutil info -plist as well as diskutil listFilesystems -plist for more detailed information.

The top-to-bottom appearance of all whole disks is sorted in numerical order by unit (whole disk) number. However, within each whole disk's "sublist" of partitions, the ordering indicates actual on-disk location. The first disk item listed represents the partition which is located most near the beginning of its encompassing whole disk, and so on.

When viewed this way, the slice (partition) parts of the BSD disk identifiers may, in certain circumstances, not appear in numerical order. This is normal and is likely the result of a recent partition map editing operation in which volumes were kept mounted.

Note that both human-readable and plist output are sorted as described above.

See the DEVICES section below for the various forms that the device specification may take for this and all of the other diskutil verbs.

     info | information [-plist] device | -all

Get detailed information about a specific whole disk or partition. If -plist is specified, then a property list instead of the normal user-readable output will be emitted. If -all is specified, then all disks (whole disks and their partitions) are processed.

     activity

Continuously display system-wide disk manipulation activity as reported by the Disk Arbitration framework until interrupted with a signal (e.g. by typing Control-C).

This can be useful to watch system-wide activity of disks coming on-line or being ejected, volumes on disks being mounted or unmounted, volumes being renamed, etc. However, this output must never be parsed; programs should become Disk Arbitra tion clients instead.

For debugging information, such as the monitoring of applications dissenting (attempting to deny) activities for disks for which they have registered an interest, you must use the logging features of the diskarbitrationd daemon. Programs needing this information must become Disk Arbitration clients.

     listFilesystems [-plist]

Show the file system personalities available for formatting in diskutil when using the erasing and partitioning verbs. This
is a subset of the complete set of personalities exported by the various file system bundles that may be installed in the system. Also shown are some shortcut aliases for common personalities. See the FORMAT section below for more details. If -plist is specified, then a property list instead of the normal user-readable output will be emitted.

     unmount | umount [force] device

Unmount a single volume. Force will force-unmount the volume (less kind to any open files; see also umount (8)).

     unmountDisk | umountDisk [force] device

Unmount an entire disk (all volumes). Force will force unmount the volumes (less kind to any open files; see also umount (8)). You should specify a whole disk, but all volumes of the whole disk are attempted to be unmounted even if you specify a partition.

     eject device

Eject a disk. Media will become offline for the purposes of being a data store for file systems or being a member of constructs such as software RAID or direct data. Additionally, removable media will become eligible for safe manual removal; automatically-removable media will begin its physical (motorized) eject sequence.

     mount [readOnly] [-mountPoint path] device

Mount a single volume. If readOnly is specified, then the file system is mounted read-only, even if the volume's underlying file system and/or device and/or media supports writing; even the super-user may not write to it; this is the same as the rdonly option to mount (8). If a -mountPoint is specified, then that path, rather than the standard path of /Volumes/VolumeName, will be used as the view into the volume file
content; a directory at that path must already exist.

     mountDisk device

Mount all mountable and UI-browsable volumes on the given partition map; that is, a mount is attempted on the directly mountable volume, if any, on each of the whole disk's partitions. However, "virtual" volumes, such as those are implied by e.g. Core Storage Physical Volumes, AppleRAID Members, etc., are not handled. You should specify a whole disk, but all volumes of the whole disk are attempted to be mounted even if you specify a partition.

     rename | renameVolume device name

Rename a volume. Volume names are subject to file system-specific alphabet and length restrictions.

     resetFusion

Repair a split Fusion Drive, see HT207584

     enableJournal device

Enable journaling on an HFS+ volume. This works whether or not the volume is currently mounted (the volume is temporarily
mounted if necessary). Ownership of the affected disk is required.

     disableJournal [force] device

Disable journaling on an HFS+ volume. This normally works whether or not the volume is currently mounted (the volume is
temporarily mounted if necessary). If the -force option is specified, then journaling is disabled directly on disk; in this case, the volume must not be mounted. Ownership of the affected disk is required.

     moveJournal external journalDevice device

Create a 512MB Apple_Journal partition using the journalDevice partition to serve as a journal for the volume device. For best results, journalDevice should be a partition on a different whole-disk than the volume itself.

The journal for device will be moved externally onto the newly created Apple_Journal partition.

Since the journalDevice you specify will invariably be larger than 512MB, a new HFS+ partition will be created following the Apple_Journal partition to fill the remaining space.

Moving the journal works whether or not the volume is mounted, provided journaling is enabled on that volume. No errors are
currently supported to flag attempts to move journals on volumes that do not have journaling enabled. If you have multiple volumes for which you want external journals, each must have its own external Apple_Journal partition. Ownership of the affected disks is required.

     moveJournal internal device

Move the journal for device back locally (onto that same device). Ownership of the affected disk is required.

     enableOwnership device

Enable ownership of a volume. The on-root-disk Volume Database at /var/db/volinfo.database is manipulated such that the User and Group ID settings of files, directories, and links (file system objects, or "FSOs") on the target volume are taken into account.

This setting for a particular volume is persistent across ejects and injects of that volume as seen by the current OS, even across reboots of that OS, because of the entries in this OS's Volume Database. Note thus that the setting is not kept on the target disk, nor is it in-memory.

For some locations of devices (e.g. internal hard disks), consideration of ownership settings on FSOs is the default. For others (e.g. plug-in USB disks), it is not.

When ownership is disabled, Owner and Group ID settings on FSOs appear to the user and programs as the current user and group instead of their actual on-disk settings, in order to make it easy to use a plug-in disk of which the user has physical possession.

When ownership is enabled, the Owner and Group ID settings that exist on the disk are taken into account for determining access, and exact settings are written to the disk as FSOs are created. A common reason for having to enable ownership is when a disk is to contain FSOs whose User and Group ID settings, and thus permissions behavior overall, is critically important, such as when the plug-in disk contains system files to be changed or added to.

See also the vsdbutil(8) command. Running as root is required.

     disableOwnership device
                Disable ownership of a volume.  See enableOwnership above.
                Running as root is required.

     verifyVolume device
                Verify the file system data structures of a volume.  The
                appropriate fsck program is executed and the volume is left
                mounted or unmounted as it was before the command.  Ownership
                of the disk to be verified is required.

     repairVolume device
                Repair the file system data structures of a volume.  The
                appropriate fsck program is executed and the volume is left
                mounted or unmounted as it was before the command.  Ownership
                of the affected disk is required.

     verifyDisk device
                Verify the partition map layout of a whole disk intended for
                booting or data use on a Macintosh.  The checks further
                include, but are not limited to, the integrity of the EFI Sys-
                tem Partition, the integrity of any Core Storage Physical Vol-
                ume partitions, and provisioning of space for boot loaders.
                Ownership of the disk to be verified is required; it must be a
                whole disk and must have a partition map.

     repairDisk device
                Repair the partition map layout of a whole disk intended for
                booting or data use on a Macintosh.  The repairs further
                include, but are not limited to, the repair or creation of an
                EFI System Partition, the integrity of any Core Storage Physi-
                cal Volume partitions, and the provisioning of space for boot
                loaders.  Ownership of the affected disk is required; it must
                be a whole disk and must have a partition map.

     eraseDisk format name [APM[Format] | MBR[Format] | GPT[Format]] device
                Erase an existing disk, removing all volumes and writing out a
                new partitioning scheme containing one new empty file system
                volume.  If the partitioning scheme is not specified, then an
                appropriate one for the current machine is chosen.  Format is
                discussed below in the section for the partitionDisk verb.
                Ownership of the affected disk is required.

     eraseVolume format name device
                Write out a new empty file system volume (erasing any current
                file system volume) on an existing partition.  The partition
                remains but its data is lost.  Format is discussed below in
                the section for the partitionDisk verb.

                If you specify Free Space for format, the partition itself is
                deleted (removed entirely) from the partition map instead of
                merely being erased.  Ownership of the affected disk is
                required.

     reformat device
                Erase an existing volume by writing out a new empty file sys-
                tem of the same personality (type) and with the same volume
                name.  Ownership of the affected disk is required.

     eraseOptical [quick] device
                Erase optical media (CD/RW, DVD/RW, etc.).  Quick specifies
                whether the disc recording system software should do a full
                erase or a quick erase.  Ownership of the affected disk is
                required.

     zeroDisk [force] device
                Erase a device, writing zeros to the media.  The device can be
                a whole-disk or a partition.  In either case, in order to be
                useful again, zero'd whole-disks will need to be (re)parti-
                tioned, or zero'd partitions will need to be (re)formatted
                with a file system, e.g. by using the partitionDisk,
                eraseDisk, or eraseVolume verbs.  If you desire a more sophis-
                ticated erase algorithm or if you need to erase only free
                space not in use for files, use the secureErase verb.  The
                force parameter causes best-effort, non-error-terminating,
                forced unmounts and shared-mode writes to be attempted; how-
                ever, this is still no guarantee against drivers which claim
                the disk exclusively. In such cases, you may have to first
                unmount all overlying logical volumes (e.g. CoreStorage or
                AppleRAID), or, if a disk is partially damaged in just the
                wrong way, even un-install a kext or erase the disk elsewhere.
                Ownership of the affected disk is required.

     randomDisk [times] device
                Erase a whole disk, writing random data to the media.  Times
                is the optional (defaults to 1) number of times to write ran-
                dom information.  The device can be a whole-disk or a parti-
                tion.  In either case, in order to be useful again, randomized
                whole-disks will need to be (re)partitioned, or randomized
                partitions will need to be (re)formatted with a file system,
                e.g. by using the partitionDisk or eraseDisk verbs.  If you
                desire a more sophisticated erase algorithm or if you need to
                erase only free space not in use for files, use the
                secureErase verb.  Ownership of the affected disk is required.

     secureErase [freespace] level device
                Erase, using a secure method, either a whole-disk (including
                any and all partitions), or, only the free space (not in use
                for files) on a currently-mounted volume.  Erasing a whole-
                disk will leave it useless until it is partitioned again.
                Erasing freespace on a volume will leave it exactly as it was
                from an end-user perspective, with the exception that it will
                not be possible to recover deleted files or data using utility
                software.  If you need to erase all contents of a partition
                but not its hosting whole-disk, use the zeroDisk or randomDisk
                verbs.  Ownership of the affected disk is required.

                Level should be one of the following:

                      •   0 - Single-pass zero-fill erase.

                      •   1 - Single-pass random-fill erase.

                      •   2 - US DoD 7-pass secure erase.

                      •   3 - Gutmann algorithm 35-pass secure erase.

                      •   4 - US DoE algorithm 3-pass secure erase.

     partitionDisk device [numberOfPartitions] [APM[Format] | MBR[Format] |
                GPT[Format]] [part1Format part1Name part1Size part2Format
                part2Name part2Size part3Format part3Name part3Size ...]

(re)Partition a disk, removing all volumes. All volumes on this disk will be destroyed. The device parameter specifies which whole disk is to be partitioned. The optional numberOfPartitions parameter specifies the number of partitions to create; if given then the number of parameter
triplets (see below) is expected to match; else, the number of triplets alone given will determine the number of partitions created.

The optional partitioning scheme parameter forces a particular partitioning scheme; if not specified, a suitable default is chosen. They are:

• APM[Format] specifies that an Apple Partition Map scheme should be used. This is the traditional Apple partitioning scheme used to start up a PowerPC-based Macintosh computer, to use the disk as a non-startup disk with any Mac, or to create a multiplatform compatible startup disk.

• MBR[Format] specifies that a Master Boot Record scheme should be used. This is the DOS/Windows-compatible partitioning scheme.

• GPT[Format] specifies that a GUID Partitioning Table scheme should be used. This is the partitioning scheme used to start up an Intel-based Macintosh computer.

For each partition, a triplet of the desired file system format, volume name, and size must be specified. Several other diskutil verbs allow these triplets as well (and for them, the numberOfPartitions parameter is also optional). The triplets must be as follows:

• Format names are of the form jhfs+, HFS+, MS-DOS, etc.; a list of formattable file systems (more precisely, specific file system personalities exported by the installed file system bundles) and common aliases is available from the listFilesystems verb.

Format guides diskutil both in what partition type to set for the partitions (slices) as well as what file system structures to initialize therein, using the file system bundle's plist's FormatExecutable setting which usually points to the appropriate formatter program such as ewfs_hfs(8).

You can specify a format of Free Space to skip an area of the disk.

You can specify the partition type manually and directly with a format of % % such as %Apple_HFS% or % % such as %48465300-0000-11AA-AA11-00306543ECAC%; these imply a name of %noformat% (below). Human-readable types must be known to the system but UUID types (GPT scheme only) can be arbitrary.

• Names are the initial volume names; they must conform to file system specific restrictions.

If a name of %noformat% is specified, then the partition is left blank such that the partition space is carved out, the partition type is set according to the file system format name or explicit type, the partition space is partially erased ("wiped"), but a file system structure is not initialized with any file system's formatter program (e.g. newfs_hfs(8);
this is useful for setting up partitions that will contain user-defined (not necessarily file system) data.

For a triplet whose format is Free Space or a directly-specified partition type, its name is ignored but a dummy name must nevertheless be
present.

• Sizes are floating point numbers followed by a letter or percent sign as described in the SIZES section at the end of this page (e.g. 165536000, 55.3T, 678M, 75%, R).

In addition to explicitly-requested partitions, space (gaps) might be allocated to satisfy certain filesystems' position
and length alignment requirements; space might be allocated for possible future booter partition insertion; and indeed,
actual booter partitions might be implicitly created.

In particular, there is a rule that unrecognized partitions 1GiB or larger automatically acquire booters. Thus, if you create an arbitrary partition with e.g. diskutil partitionDisk disk0 gpt %11112222-1111-2222-1111-111122221111% %noformat% 3gib jhfs+ Untitled r, then a booter partition will also be created. You can always delete that booter with diskutil eraseVolume "Free Space" dummy disk0s3.

The last partition is usually automatically lengthened to the end of the partition map (disk). You can specify an exact size for your last partition by specifying it as the penultimate triplet and specifying an additional (last) triplet as Free Space. Or you can use the R (remainder) size specifier for one of your middle partitions while specifying an exact size for your last partition.

Ownership of the affected disk is required.

     resizeVolume device [ limits | mapsize | R | size [numberOfPartitions]
                [part1Format part1Name part1Size part2Format part2Name
                part2Size part3Format part3Name part3Size ...] ]

Non-destructively resize a volume (partition); you may increase or decrease its size. Alternatively, takes no action and prints some info.

A size of limits takes no action, but instead will print the range of valid values for the target partition, taking into account current file system and partition map conditions such as files in use and other (immovable) partitions following the target.

A size of mapsize takes no action, but instead will print the size of the encompassing whole-disk device, as well as the size of the entire partition map (all partitions less map overhead). The whole-disk device might be larger than the partition map if the whole-disk device has grown since the partition map was created. Growing a whole-disk device is possible with certain enterprise disk (RAID) systems.

You can grow a volume (partition) (back) to its maximum size possible, provided no new partitions have been created that are in the way, by specifying R for the new volume size. You should use R instead of attempting an absolute value such as 100% because the latter cannot count partition map overhead.

When decreasing the size, new partitions may optionally be created to fill the newly-freed space. To do this, specify the numberOfPartitions, format, name, and size parameters in the same manner as the triplet description for the partitionDisk verb.

Resizing a volume that is currently set as the computer's startup disk will invalidate that setting; use the Startup Disk System Preferences panel or bless (8) to reset the resized volume as the startup disk.

Device refers to a volume; the volume's file system must be journaled HFS+. Valid sizes are a number followed by a capital letter multiplier or percent sign suffix as described in the SIZES section at the end of this page (e.g. 1.5T, 128M, 50%). Ownership of the affected disk is required.

     splitPartition device [numberOfPartitions] [part1Format part1Name
                part1Size part2Format part2Name part2Size part3Format
                part3Name part3Size ...]

Destructively split a volume into multiple partitions. You must supply a list of new partitions to create in the space of
the old partition; specify these with the numberOfPartitions, format, name, and size parameters in the same manner as the
triplet description for the partitionDisk verb.

For one of your triplets, you can optionally specify the R meta-size in lieu of a constant number value for the size
parameter: the substituted value will be exactly the amount of space necessary to complete the re-filling of the original
partition with all of your triplets.

Device refers to a volume. Ownership of the affected disk is required.

     mergePartitions [force] format name fromDevice toDevice

Merge two or more partitions on a disk. All data on merged partitions other than the first will be lost. Data on the first partition will be lost as well if the force argument is given.

If force is not given, and the first partition has a resizable file system (e.g. JHFS+), the file system will be preserved and grown in a data-preserving manner; your format and name parameters are ignored in this case. If force is not given, and the first partition is not resizable, you are prompted if you want to format. You will also be prompted to format if the first partition has an (HFS) Allocation Block Size which
is too small to support the required growth of the first partition; see the -b option for newfs_hfs (8).

If force is given, the final resulting partition is always (re)formatted. You should do this if you wish to (re)format to a new file system type. You will be prompted to confirm.

Format and name must always be given, but they have an effect only when force is given.

Merged partitions are required to be ordered sequentially on disk (see diskutil list for the actual on-disk ordering). All partitions in the range, except for the first one, must be unmountable. Ownership of the affected disk is required.

     APFS | ap apfsVerb [...]

Apple APFS is a system of virtual volumes. APFS verbs can be used to create, manipulate and destroy APFS Containers and
their APFS Volumes. Apple APFS defines these types of objects:

• Container - An APFS Container imports one or more APFS Physical Store disks and exports zero or more APFS Volume disks. Zero or more APFS Containers can exist in (might be attached to) the system at any one time.

While attached, the "handle" by which an APFS Container is identified is by its APFS Container Reference disk (device). You should treat this as an opaque reference token.

The Container Reference disk is a synthesized whole disk which is exported by APFS for identification purposes only; it has no storage. It is associated with the AppleAPFSContainerScheme node in the IO Registry. While APFS Volume device identifiers appear to be of a related form, you should never use the Container Reference as a basis to create device identifiers yourself; use the listing verbs with their plist options instead.

• Physical Store - An APFS Physical Store is a disk which is imported into (that is, which backs, indeed defines) an APFS Container. An APFS Container can import more than one Physical Store.

An APFS Physical Store disk is not necessarily a disk from a partition map; it could be e.g. an AppleRAID Set disk. Therefore, you must never assume that an APFS Physical Store's disk identifier is a 2-part form such as disk0s2.

• Volume - An APFS Volume is an [un]mountable file system volume which is exported from an APFS Container. Zero or more APFS Volumes may be exported out of an APFS Container.

APFS Volumes have no specified "size" (capacity). Instead, all APFS Volumes consume capacity out of the remaining free space of their parent APFS Container, consuming or returning such capacity as user file data is added or deleted. Note that this means
that all Volumes within a Container compete for the Container's remaining capacity. However, you can manage Volume allocation with the optional reserve and quota size values.

The optional reserve size requests an assured minimum capacity for an APFS Volume. If successfully created, the Volume is guaranteed to be able to store at least this many bytes of user file data. Note that beyond this, the Volume might be able to store even more until constrained by reaching zero free space in its parent Container or by reaching a quota, if any. You can use a reserve to prevent running out of capacity due to competition from other Volumes or from a Container shrink attempt.

The optional quota size applies a maximum capacity to an APFS Volume, placing a limit on the number of bytes of user file data which can be stored on the Volume. Note that you might not be able to reach this limit if its parent Container becomes full first. You can use a quota to enforce accounting or to manage against "unfair" premature filling-up of the parent Container due solely to this Volume at the expense of sibling Volumes.

Efficient file copy cloning (copy-on-write) is supported (see copyfile (3)'s COPYFILE_CLONE).

Optional file-level encryption is supported.

The format of an APFS Volume's device identifier is that of a slice disk of a special whole-disk; both disks are synthesized by APFS. The "whole" identifier number (a positive possibly-multi-digit integer) is arbitrary, and the "slice" numbers (positive possibly-multi-digit integers) count up from 1 with each new Volume. Deleting Volumes may cause gaps in the numbering until the next eject/attach cycle.
This form appears the same as a partition (map) scheme and partitions, but it is completely unrelated. For example: If "disk3s2" is a Physical
Store defining a Container, then "disk5s1","disk5s2", and "disk5s3" might be the Container's Volumes; "disk5" exists but is never used directly.

Although it has a device node, an APFS Volume's data may only be accessed through its files; you cannot open an APFS Volume device node to "directly" access its on-disk bytes.

• Snapshot - An APFS Volume can have zero or more associated APFS Snapshots. An APFS Snapshot appears as a read-only copy of its parent APFS Volume at a frozen moment in time. Snapshots are neither listed nor discoverable when their Volume is not mounted.

APFS itself has no provision for backing up your data. Backups should be always be performed on a regular basis and before modifying any APFS Container using these commands.

The following is a list of APFS sub-verbs with their descriptions and individual arguments.

                list [-plist]
                           Display, as a tree, all current APFS objects in the
                           system with any associated disks and status.

                           If -plist is specified, then a property list will
                           be emitted instead of the normal user-readable out-
                           put.

                deleteContainer containerReferenceDevice | physicalStoreDevice [name]
                           Destroy an existing APFS Container, including all of its APFS Volumes.
                           The APFS Volumes are unmounted first; this process may not succeed if
                           one or more is busy.
                           If this happens, the operation is cancelled and everything is left intact.
                           Otherwise, all APFS Volumes are deleted as well as its
                           APFS Container, and the APFS Container's former Physical Store disks
                           will be reformatted as HFS; data on all APFS Volumes will be lost.

                           You can optionally specify a new name, or else  "Untitled" will
                           be chosen.  If there were multiple Physical Stores, a space 
                           and a number suffix is added for each.

                           Specifying an APFS Physical Store (instead of an  APFS Container)
                           activates an alternate last-resort mode which you can use to reclaim use of
                           your disk(s) even though they may be unusable due to being damaged
                           yet un-deletable due to being busy.

                           Ownership of the affected disks is required.

                deleteVolume volumeDevice
                           Remove the given APFS Volume from its APFS Container.
                           All of the Volume's data will be lost.

                           Ownership of the affected disks is required.

                unlockVolume | unlock volumeDevice [-user disk | cryptoUserUUID]
                           [-passphrase passphrase] | [-stdinpassphrase]
                           [-nomount | -mountpoint mountpoint] [-verify]
                          
                           Unlock and mount an encrypted and locked APFS Volume or verify a passphrase.

                           If you do not supply the -user option, then all cryptographic users
                           on that APFS Volume are searched for a match;
                           if you supply disk then the Disk UUID (which equals the APFS Volume UUID)
                           is assumed; if you supply a UUID then that specific user is assumed.

                           You will be prompted interactively for a passphrase unless you specify
                           a passphrase parameter with -passphrase or pipe your passphrase into
                           stdin and use -stdinpassphrase.

                           You can skip the explicit mounting step or specify a "custom" mountpoint
                           with the -nomount or -mountpoint options. If you specify your own mount- point 
                           path, it must exist and you must have write privileges on it.

                           Specifying -verify will test passphrase correctness without affecting the
                           locked or unlocked state.

                           To re-lock the volume, unmount it, e.g. with diskutil unmount.

                           Ownership of the affected disks is required.

     appleRAID | ar raidVerb [...]
                AppleRAID verbs can be used to create, manipulate and destroy
                AppleRAID volumes (Software RAID).  AppleRAID supports three
                basic types of RAID sets:

                      •   "stripe" - Striped Volume (RAID 0)

                      •   "mirror" - Mirrored Volume (RAID 1)

                      •   "concat" - Concatenated Volume (Spanning)

                Of these three basic types, only the "mirror" type increases
                fault-tolerance.  Mirrors may have more than two disks to fur-
                ther increase their fault-tolerance.  Striped and concaten-
                tated volumes are, in fact, more vulnerable to faults than
                single disk volumes.

                From these basic types, "stacked" or "nested" RAID volumes can
                be created.  Stacked RAID sets that make use of mirrored RAID
                sets are fault-tolerant.  For example, these are some of the
                more common combinations of stacked RAID sets:

                      •   RAID 50 - A striped RAID set of hardware RAID 5
                          disks.

                      •   RAID 10 - A striped RAID set of mirrored RAID sets.

                      •   RAID 0+1 - A mirrored RAID set of striped RAID sets.

                      •   Concatenated Mirror - A concatenation of mirrored
                          RAID sets.

                When creating new RAID sets or adding disks, if possible, it
                is better to specify the entire disk instead of a partition on
                that disk.  This allows the software to reformat the entire
                disk using the most current partition layouts.  When using
                whole disks, the type of partitioning used is selected based
                on the platform type (PPC = APMFormat, Intel = GPTFormat).
                GPT and APM partition formats cannot be mixed in the same RAID
                set.

                In addition to whole disk and partition device names,
                AppleRAID uses UUIDs to refer to existing RAID sets and their
                members.  Existing RAID sets may also be specified by mount
                point (e.g.  /Volume/raidset). In many cases, using the UUID
                for the device argument is preferred because disk device names
                may change over time when disks are added, disks are removed
                or when the system is rebooted.  If RAID members have been
                physically disconnected from the system or are no longer
                responding, you must use the member's UUID as the command
                argument.  Messages in the system log will refer to RAID sets
                and their member disks by UUID.  For more information on spec-
                ifying device arguments see the "DEVICES" section below.

                AppleRAID is not a replacement for backing up your data.
                Backups should be always be performed on a regular basis and
                before modifying any RAID set using these commands.

                The following is a list of appleRAID sub-verbs with their
                descriptions and individual arguments.

                list [-plist | UUID]
                           Display AppleRAID volumes with current status and
                           associated member disks.  If UUID is specified,
                           only list the RAID set with that AppleRAID Set
                           UUID.  If -plist is specified, then a property list
                           will be emitted instead of user-formatted output.
                           The -plist and UUID arguments may not both be spec-
                           ified.  diskutil listRAID and diskutil checkRAID
                           are deprecated synonyms for diskutil appleRAID
                           list.

                create mirror | stripe | concat setName format devices ...
                           Create a new RAID set consisting of multiple disks
                           and/or RAID sets.  setName is used for both the
                           name of the created RAID volume and the RAID set
                           itself (as displayed in list). e.g. 'diskutil cre-
                           ateRAID stripe MyArray JHFS+ disk1 disk2 disk3
                           disk4'.  Ownership of the affected disks is
                           required.  diskutil createRAID is a deprecated syn-
                           onym for diskutil appleRAID create.

                delete raidVolume
                           Destroy an existing RAID set.  If the RAID set is a
                           mirror with a resizable file system, delete will
                           attempt to convert each of the member partitions
                           back into a non-RAID volume while retaining the
                           contained file system.  For concatenated RAID sets
                           with a resizable file system, delete will attempt
                           to shrink the file system to fit on the first mem-
                           ber partition and convert that to a non-RAID vol-
                           ume.  Ownership of the affected disks is required.
                           diskutil destroyRAID is a deprecated synonym for
                           diskutil appleRAID delete.

                repairMirror raidVolume newDevice
                           Repair a degraded mirror by adding a "new" disk
                           given as newDevice to the RAID mirror set whose
                           exported disk device or set UUID is given as
                           raidVolume. The new disk must be the same size or
                           larger than the existing disks in the RAID set.
                           After running this command, you should manually
                           remove the old (orphaned, failed) member(s) with
                           diskutil appleRAID remove. Ownership of the
                           affected disk is required.  diskutil repairMirror
                           is a deprecated synonym for diskutil appleRAID
                           repairMirror.

                add type newDevice raidVolume
                           Add a new member or hot spare to an existing RAID
                           set.  Type can be either member or spare.  New
                           disks are added live, the RAID volume does not need
                           to be unmounted.  Mirrored volumes support adding
                           both members and hot spares, concatenated volumes
                           only support adding members.  When adding to a mir-
                           rored RAID set, the new disk must be the same size
                           or larger than the existing disks in the RAID set.
                           Adding a hot spare to a mirror will enable autore-
                           building for that mirror.  Adding a new member to a
                           concatenated RAID set appends the member and
                           expands the RAID volume.  Ownership of the affected
                           disk is required.  diskutil addToRAID is a depre-
                           cated synonym for diskutil appleRAID add.

                remove oldDevice raidVolume
                           Remove a member or spare from an existing RAID set.
                           Old disks are removed live; the RAID volume does
                           not need to be unmounted.  For missing devices,
                           oldDevice must be the device's UUID.  Online mirror
                           members with a resizable file system will be con-
                           verted to non-RAID volumes, spare and offline mem-
                           bers will be marked free.  For concatenated RAID
                           sets, only the last member can be removed.  For
                           resizable file systems remove will first attempt to
                           shrink the concatenated RAID set so that the file
                           system fits on the remaining disks.  Ownership of
                           the affected disk is required.  diskutil
                           removeFromRAID is a deprecated synonym for diskutil
                           appleRAID remove.

                enable mirror | concat device
                           Convert a non-RAID disk partition containing a
                           resizable file system (such as JHFS+) into an
                           unpaired mirror or single disk concatenated RAID
                           set.  Disks that were originally partitioned on Mac
                           OS X 10.2 Jaguar or earlier or were partitioned to
                           be Mac OS 9 compatible may not be resizable.  Own-
                           ership of the affected disk is required.  diskutil
                           enableRAID is a deprecated synonym for diskutil
                           appleRAID enable.

                update key value raidVolume
                           Update the key value parameters of an existing RAID
                           set.  Valid keys are:

                                 •   AutoRebuild - If true, the system
                                     attempts to rebuild degraded mirrored
                                     volumes automatically.  When looking for
                                     devices for rebuild, AppleRAID first
                                     looks for hot spares and then degraded
                                     members.  Use a value of "1" for true and
                                     "0" for false.

                                 •   SetTimeout - Controls how long the system
                                     waits (in seconds) for a missing device
                                     before degrading a mirrored raid set.
                                     Also controls the amount of time you have
                                     to disconnect all devices from an
                                     unmounted mirror without degrading it.

                           Ownership of the affected disk is required.
                           diskutil updateRAID is a deprecated synonym for
                           diskutil appleRAID update.

     coreStorage | cs coreStorageVerb [...]
                CoreStorage verbs can be used to create, manipulate and
                destroy CoreStorage volumes.

                CoreStorage maintains a world of virtual disks, somewhat like
                RAID, in which one can easily add or remove imported backing
                store disks, as well as exported usable volumes, to or from a
                pool (or several pools). This provides the user with flexibil-
                ity in allocating their hardware; user or operating system
                data can span multiple physical disks seamlessly, for example.

                Apple CoreStorage defines four types of objects, instances of
                which are uniquely represented by a UUID:

                      •   Logical Volume Group (LVG)

                      •   Physical Volume (PV)

                      •   Logical Volume Family (LVF)

                      •   Logical Volume (LV)

                The Logical Volume Group (LVG) is the top or "pool" level;
                zero or more may exist during any OS boot time session.

                An LVG imports one or more Physical Volumes (PVs). A PV repre-
                sents a device that feeds the LVG storage space; a PV is nor-
                mally real media but it can be a disk image or even an
                AppleRAID Set. A disk offered to be a PV must be a partition
                and the encompassing scheme must be GPT.

                An LVG exports zero or more Logical Volume Families (LVFs). An
                LVF contains properties which govern and bind together all of
                its descendant Logical Volumes (LVs). These properties provide
                settings for Full Disk Encryption (FDE) (such as whether the
                LVG is encrypted, which users have access, etc) and other ser-
                vices.  However, at the present time, for new LVF creation,
                only zero or one LVF per LVG is supported.

                A Logical Volume Family (LVF) exports one or more Logical Vol-
                umes (LVs).  However, at the present time, only and exactly
                one LV per LVF is supported.

                A Logical Volume (LV) exports a dev node, upon which a file
                system (such as Journaled HFS+) resides.

                For more information on specifying device arguments, see the
                DEVICES section below.

                CoreStorage is not a replacement for backing up your data.
                Backups should be always be performed on a regular basis and
                before modifying any CoreStorage volumes using these commands.

                The following is a list of coreStorage sub-verbs with their
                descriptions and individual arguments.

                list [-plist | UUID]
                           Display a tree view of the CoreStorage world for
                           all current logical volume groups (LVGs) with mem-
                           ber disks (PVs) and exported volumes (LVFs and
                           LVs), with properties and status for each level.
                           If -plist is specified then a property list will be
                           emitted instead of the formatted tree output; the
                           UUIDs can be used with the diskutil coreStorage
                           information verb to get properties for the object
                           represented by that UUID.  If UUID is specified
                           then an attempt is made to list only that UUID
                           (whatever type of CoreStorage object it may repre-
                           sent).  The -plist and UUID arguments may not both
                           be specified.

                info | information [-plist] UUID | device
                           Display properties of the CoreStorage object (LVG,
                           PV, LVF, or LV) associated with the given CoreStor-
                           age UUID or disk.

                convert device [-stdinpassphrase | -passphrase [passphrase]]
                           Convert a regular Journaled HFS+ or Case-sensitive
                           Journaled HFS+ volume (must be on a partition and
                           within a GPT partitioning scheme) into a CoreStor-
                           age logical volume.

                           If -passphrase is specified, the on-disk bytes will
                           be encrypted. You will be prompted for a new
                           passphrase interactively, or you can specify the
                           passphrase on the command line. Alternatively, if
                           you specify -stdinpassphrase the standard input is
                           read for the passphrase so that a program could
                           execute diskutil and send the passphrase through a
                           pipe without having to expose it as a command-line
                           parameter.

                           The volume must be resizable (the above types are)
                           and also mounted. Conversion is done live and in-
                           place; targeting the boot volume is supported; as
                           much of the conversion as possible is done before
                           an eject or reboot is necessary.

                           After slightly shrinking the source volume to make
                           room for CoreStorage data structures at the end,
                           its partition type is changed to Apple_CoreStorage
                           and it becomes a CoreStorage Physical Volume.  A
                           new CoreStorage Logical Volume Group is then cre-
                           ated with this Physical Volume as the backing
                           store, followed by the creation of a Logical Volume
                           Family and Logical Volume pair.

                           At this point, the new CoreStorage PV/LVG/LVF/LV
                           stack is ready for use, although the "old" mount-
                           point must first be unmounted; yet it might not be
                           unmountable. This will occur if the target (now the
                           PV) is the current boot volume.

                           Just before exiting, diskutil coreStorage convert
                           will try to unmount the target disk (which is now
                           the "old" mount point and the new PV). If success-
                           ful (target is not the boot disk), the volume now
                           becomes mounted from the LV. If unsuccessful (tar-
                           get is the boot disk), a reboot is necessary.

                           At this point, if no encryption was specified, all
                           is done. Otherwise, the bytes-on-disk will begin to
                           be encrypted in-place by CoreStorage automatically
                           "in the background" while the PV/LVG/LVF/LV stack
                           continues to be usable. Encryption progress may be
                           monitored with diskutil coreStorage list.

                           When encryption is finished, a passphrase will be
                           required the next time the LV is ejected and re-
                           attached.  If the LV is hosting the boot volume,
                           this passphrase requirement will thus occur at the
                           next reboot.

                           Note that all on-disk data is not secured immedi-
                           ately; it is a deliberate process of encrypting all
                           on-disk bytes while the CoreStorage driver keeps
                           publishing the (usable) LVG/LV.

                           Ownership of the affected disk is required.

                revert device | lvUUID [-stdinpassphrase] | [-passphrase
                           passphrase] | [-recoverykeychain file]
                           Convert a CoreStorage logical volume back to its
                           native type.  The volume must have been created by
                           means of conversion, e.g. with diskutil coreStorage
                           convert.

                           If the volume was not created with a passphrase,
                           then simple ownership of the affected disk is
                           required; otherwise, a passphrase must be supplied,
                           either interactively or via one of the parameters
                           or a keychain file in the same manner as:
                            diskutil coreStorage unlockVolume.

                create | createLVG lvgName devices ...
                           Create a CoreStorage logical volume group. The
                           disks specified will become the (initial) set of
                           physical volumes; more than one may be specified.
                           You can specify partitions (which will be re-typed
                           to be Apple_CoreStorage) or whole-disks (which will
                           be partitioned as GPT and will contain an
                           Apple_CoreStorage partition).  The resulting LVG
                           UUID can then be used with createVolume below.  All
                           existing data on the drive(s) will be lost.  Owner-
                           ship of the affected disk is required.

                delete | deleteLVG lvgUUID | lvgName
                           Delete a CoreStorage logical volume group. All log-
                           ical volume families with their logical volumes are
                           removed, the logical volume group is destroyed, and
                           the now-orphaned physical volumes are erased and
                           partition-typed as Journaled HFS+.

                rename | renameLVG lvgUUID | lvgName newName
                           Rename a CoreStorage logical volume group. Do not
                           confuse this name with the LV name or the volume
                           name of the file system volume on the LV.

                createVolume | createLV lvgUUID | lvgName type name size
                           [-stdinpassphrase | -passphrase [passphrase]]
                           Export a new logical volume family, with a new log-
                           ical volume under it, out of a CoreStorage logical
                           volume group.  Type is the file system personality
                           to initialize on the new logical volume. Valid
                           types are Journaled HFS+ or Case-sensitive Jour-
                           naled HFS+ or their aliases.  Size is the amount of
                           space to allocate from the parent LVG. It is given
                           in the same manner as the triplet description for
                           the partitionDisk verb, and you can also specify
                           with % a percentage of the currently remaining
                           unallocated space in the LVG.

                           If -passphrase or -stdinpassphrase is specified, in
                           the same manner as with diskutil coreStorage
                           convert above, on-disk data will be stored in an
                           encrypted form as the Logical Volume is filled;
                           otherwise, the data will remain plain.

                deleteVolume | deleteLV lvUUID | device
                           Remove an exported logical volume (and its logical
                           volume family as appropriate) from a CoreStorage
                           logical volume group. Any data on that logical vol-
                           ume will be lost.  This operation will thus result
                           in an increase in free space in the logical volume
                           group.

                           It is assumed that the logical volume is used as a
                           backing store for a file system; therefore, an
                           unmount attempt is made which must succeed before
                           the removal of the logical volume is done.

                encryptVolume | encryptLV lvUUID | device [-stdinpassphrase] |
                           [-passphrase passphrase]
                           Begin a live background process of encrypting the
                           on-disk backing bytes of an existing plain
                           CoreStorage logical volume (LV).

                           That is, the on-disk bytes that are backing the
                           user data are all visited, read, and re-written in
                           an encrypted form; this process can take a long
                           time (minutes to hours). This process continues
                           seamlessly across reboots. The logical volume
                           remains usable at all times.  When this command
                           returns, the operation will be ongoing; you can
                           check progress with diskutil coreStorage list.

                           The entire logical volume family (LVF) is affected
                           since all LVs in an LVF share the same encryption
                           settings.

                           Any new user data written while this background
                           operation is in progress will be in encrypted form.

                           Specifying -passphrase or -stdinpassphrase or
                           interactively entering a passphrase is mandatory;
                           you do so in the same manner as with diskutil
                           coreStorage convert above.

                           The volume is encrypted with an FDE "Disk"
                           passphrase, which is distinct from the "User" ID
                           and passphrase combination which FileVault asso-
                           ciates with a volume.  Therefore, if you want to
                           encrypt a macOS "OS-bearing" volume (with its user
                           accounts), you must use FileVault in Security Pref-
                           erences or the contextual menu in the Finder.

                decryptVolume | decryptLV lvUUID | device [-stdinpassphrase] |
                           [-passphrase passphrase]
                           Begin a live background process of decrypting the
                           on-disk backing bytes of an existing encrypted
                           CoreStorage logical volume (LV). Bytes are read,
                           decrypted, and written back to disk in plain form.
                           The LV must be unlocked before beginning this oper-
                           ation.

                           Like as in diskutil coreStorage encryptVolume
                           above, all on-disk bytes are visited and converted,
                           the process is seamless across reboots, the logical
                           volume remains usable at all times, the entire log-
                           ical volume family (LVF) is affected, any new user
                           data written will be in plain form, and the opera-
                           tion will be ongoing when this command returns.

                           Credentials must be supplied; you can use
                           -passphrase or -stdinpassphrase or specify that a
                           recovery keychain file be used, in the same manner
                           as diskutil coreStorage unlockVolume.

                unlockVolume | unlockLV lvUUID [-stdinpassphrase] |
                           [-passphrase passphrase] | [-recoverykeychain file]
                           Unlock a logical volume and file system, causing it
                           to be attached and mounted.

                           Data is then accessible in plain form to the file
                           system and applications, while the on-physical-disk
                           backing bytes remain in encrypted form.

                           The locked state means that the CoreStorage driver
                           has not been given authentication information (a
                           passphrase) to interpret the encrypted bytes on
                           disk and thus export a dev node.  This verb unlocks
                           a logical volume family (LVF) and its logical vol-
                           umes (LVs) by providing that authentication; as the
                           LVs thus appear as dev nodes, any file systems upon
                           them are automatically mounted.

                           To "re-lock" the volume, make it offline again by
                           ejecting it, e.g. with diskutil eject.

                           Credentials must be supplied. You must either enter
                           a passphrase interactively, specify one of the
                           -passphrase or -stdinpassphrase parameters in the
                           same manner as with diskutil coreStorage convert
                           above, or specify that a recovery keychain file be
                           used.

                           You can specify -recoverykeychain with a path to a
                           keychain file.  The keychain must be unlocked; see
                           security(1) for more information.

                changeVolumePassphrase | passwd lvUUID [-recoverykeychain
                           file] [-oldpassphrase oldpassphrase]
                           [-newpassphrase newpassphrase] [-stdinpassphrase]
                           Change the passphrase of an existing encrypted vol-
                           ume. It need not be unlocked nor mounted. The
                           parameters, while variously optional, must be given
                           in the above order.

                           You must authenticate either via the -oldpassphrase
                           parameter, via the -stdinpassphrase parameter (with
                           newline or eof-terminated data given to stdin), or
                           via an interactive prompt (if no parameters are
                           given), in the same manner as diskutil coreStorage
                           convert above.  Alternatively, you can authenticate
                           by specifying -recoverykeychain with a path to a
                           keychain file.

                           A new passphrase must be supplied, again via one of
                           the three methods above (interactive,
                           -newpassphrase, or -stdinpassphrase).

                           If you are supplying both the old and new
                           passphrases via stdin, they must be separated with
                           a newline character.

                resizeVolume | resizeLV lvUUID | device size
                           Resize a logical volume (LV). If you shrink an LV,
                           more space becomes available in its logical volume
                           group (LVG); if you grow an LV, less space becomes
                           available. You can check the free space with
                           diskutil coreStorage list. The file system volume
                           which resides inside the LV is grown or shrunk as
                           needed.

                           You can specify a size of zero (0) to fill up all
                           remaining space in the parent LVG with the given
                           LV.

                resizeDisk | resizePV pvUUID size [part1Format part1Name
                           part1Size part2Format part2Name part2Size
                           part3Format part3Name part3Size ...]
                           Resize a physical volume (PV). If you shrink a PV,
                           less space becomes available in its logical volume
                           group (LVG); if you grow a PV, more space becomes
                           available. The partition in which the PV resides is
                           changed to accommodate, and the associated booter
                           partition, if present, is automatically moved.

                           Note that you cannot ordinarily grow a PV unless
                           there is free space in the partition map beyond it;
                           note also that you cannot ordinarily shrink a PV
                           unless the LVG has some free space in it (e.g. by
                           shrinking an overlying LV first).

                           When decreasing the size (shrinking), new parti-
                           tions may optionally be created to fill the newly-
                           freed space.  To do this, specify the format, name,
                           and size parameters in the same manner as the
                           triplet description for the partitionDisk verb.

                           You can specify a size of zero (0) to fill up all
                           remaining space to the next partition or the end of
                           the partition map, if possible.

                resizeStack lvUUID | device [pvUUID] size [part1Format
                           part1Name part1Size part2Format part2Name part2Size
                           part3Format part3Name part3Size ...]
                           Combine the actions of diskutil coreStorage
                           resizePV and diskutil coreStorage resizeLV in the
                           correct sequence in order to effect a shrink or a
                           grow in an entire LVG setup.

                           This is done by making a change to the size of a
                           logical volume (LV), after or before which (one of
                           its) physical volume(s) (PV) also changes its size
                           accordingly.  The (HFS) file system "on top of" the
                           LV and the disk partition "below" the PV, as well
                           as the location of the PV's associated booter par-
                           tition, are automatically adjusted.

                           When decreasing the size (shrinking), new parti-
                           tions may optionally be created to fill the newly-
                           freed space.  To do this, specify the format, name,
                           and size parameters in the same manner as the
                           triplet description for the partitionDisk verb.

                           Since an LVG might have one (e.g. Full Disk Encryp-
                           tion (FDE), aka FileVault), two (e.g. Fusion), or
                           even three (certain Boot Camp configurations) PVs,
                           a specific PV must be chosen. You can have this
                           command choose one for you, or you can specify the
                           PV UUID directly. If you do not specify a PV, the
                           one which has previously been marked for this pur-
                           pose is used; if no mark, a policy algorithm is
                           applied.

                           If your new LV size represents a grow of the exist-
                           ing LV size, then the PV size will take up more
                           space on disk, thus creating a larger LVG for the
                           larger LV to live in.  If your new LV size repre-
                           sents a shrink, then the PV size will take up less
                           space on disk, thus creating a smaller LVG, which
                           is enough for the smaller LV to live in. The magni-
                           tude of the size change you specify (which is for
                           the LV) causes an exact size change in the PV if
                           you conform to partition rounding (alignment)
                           restrictions; the corresponding LV change may be
                           greater because it is under additional alignment
                           restrictions imposed by CoreStorage and HFS.

                           The "spilling over" of size change effects from one
                           PV onto another is not supported; only and exactly
                           one PV is affected by this operation. Grows or
                           shrinks whose effects don't "fit" the designated PV
                           will result in an error message and no effect.  For
                           example, you can't do a shrink on a multi-PV setup
                           such that the designated PV should shrink to zero
                           size and so effectively should disappear.  Nor can
                           you do a grow which would necessitate the growth of
                           some other PV or the addition of new PVs.

                           As in diskutil coreStorage resizePV, note that you
                           cannot grow unless there is free space in the par-
                           tition map beyond the designated PV, which is not
                           normally the case because you usually don't leave
                           gaps of free space on your disk.

                           You can specify a size of zero (0) to fill up all
                           remaining space to the partition following the des-
                           ignated PV's booter or to the end of the partition
                           map, if possible.

Devices

A device parameter to any of the above commands (except where explicitly required otherwise) can usually be any of the following:

• The disk identifier (see below). Any entry of the form of disk*, e.g. disk1s9.

• The device node entry containing the disk identifier. Any entry of the form of /dev/disk*, e.g. /dev/disk2.

• The volume mount point. Any entry of the form of /Volumes/*, e.g. /Volumes/Untitled. In most cases, a "custom" mount point e.g. /your/custom/mountpoint/here is also accepted.

• The URL form of any of the volume mount point forms described above. E.g. file:///Volumes/Untitled or file:///.

• A UUID. Any entry of the form of e.g. 11111111-2222-3333-4444-555555555555. The UUID can be a "media" UUID which IOKit places in an IOMedia node as derived from e.g. a GPT map's partition UUID, or it can be an AppleRAID (or CoreStorage) set (LV) or member (PV) UUID.

Disk Identifier

The disk identifier string variously identifies a device unit, a session upon that device, or a partition (slice) upon that session. It may take
the form of diskU, diskUsS, diskUsQ, or diskUsQsS, where U, S, and Q are positive decimal integers (possibly multi-digit), and where:

• U is the device unit. It may refer to hardware (e.g. a hard drive, optical drive, or memory card) or a "drive" constructed by software (e.g. an AppleRAID set or a disk image).

• Q is the session and is only included for optical media; it refers to the number of times recording has taken place on the currently-inserted medium (disc).

• S is the slice; it refers to a partition. Upon this partition, the raw data that underlies a user-visible file system is usually present, but it may also contain specialized data for certain 3rd-party database programs, or data required for the system software (e.g. EFI or booter partitions, or APM partition map data).

Some units (e.g. floppy disks, RAID sets) contain file system data upon their "whole" device instead of containing a partitioning scheme with
partitions.

Note that the forms diskUsQ and diskUsS appear the same and must be distinguished by context. For non-optical media, this two-part form identifies a slice upon which (file system) data is stored. For optical media, it identifies a session upon which a partitioning scheme (with its slices with file systems) is stored.

Sizes

Wherever a size is emitted as an output, it is presented as a base-ten approximation to the precision of one fractional decimal digit and a
base-ten SI multiplier, often accompanied by a precise count in bytes. Scripts should refrain from parsing this human-readable output and use the -plist option instead.

Wherever a size is to be supplied by you as an input, you can provide values in several different ways, some absolute and some context-sensi tive. All suffixes described below are interpreted in a case-insensitive manner. The B is optional.

The most common way is to specify absolute values as a decimal number, possibly followed by a period and a decimal fraction, followed without whitespace with a suffix as follows:

• B is bytes (not blocks) where the multiplier is 1. This suffix may be omitted.
• K[B] is power of ten kilobytes where the multiplier is 1000 (1 x 10^3).
• M[B] is power of ten megabytes where the multiplier is 1000000 (1 x 10^6).
• G[B] is power of ten gigabytes where the multiplier is 1000000000 (1 x 10^9).
• T[B] is power of ten terabytes where the multiplier is 1000000000000 (1 x 10^12).
• P[B] is power of ten petabytes where the multiplier is 1000000000000000 (1 x 10^15).
• E[B] is power of ten exabytes where the multiplier is 1000000000000000000 (1 x 10^18).

You can also use the following suffixes:

• S | UAM ("sectors") is 512-byte units (device-independent) where the multiplier is always 512.
• DBS ("device block size") is the device-dependent native block size of the encompassing whole disk, if applicable, where the
multiplier is often 512, but not always; indeed it might not be a power of two.
• Ki[B] is power of two kibibytes where the multiplier is 1024 (1 x 2^10).
• Mi[B] is power of two mebibytes where the multiplier is 1048576 (1 x 2^20).
• Gi[B] is power of two gibibytes where the multiplier is 1073741824 (1 x 2^30).
• Ti[B] is power of two tebibytes where the multiplier is 1099511627776 (1 x 2^40).
• Pi[B] is power of two pebibytes where the multiplier is 1125899906842624 (1 x 2^50).
• Ei[B] is power of two exbibytes where the multiplier is 1152921504606846976 (1 x 2^60).

In certain contexts (e.g. when specifying partition triplets) you can provide a relative value as follows:

• % (with a preceding number) is a percentage of the whole-disk size, the partition map size, or other allocatable size, as
appropriate by context. Use of % is not supported in all situations.

• R (with no preceding number) specifies the remainder of the whole-disk size or other allocatable size after all other
triplets in the group are taken into account. It need not be in the last triplet. It must only appear in at most one
triplet among all triplets. Use of R is not supported in all situations.

You can provide an operating system-defined constant value as follows:

• %recovery% (with no preceding number) is the customary size of macOS Recovery Partitions.

Note again that B refers to bytes and S and UAM refer to a constant multiplier of 512; the latter are useful when working with tools such as gpt (8) or df (1). Note also that this multiplier is not a "block" size as actually implemented by the underlying device driver and/or hardware, nor
is it an "allocation block", which is a file system's minimum unit of backing store usage, often formatting-option-dependent.

Examples: 10G (10 gigabytes), 4.23tb (4.23 terabytes), 5M (5 megabytes), 4GiB (exactly 2^32 bytes), 126000 (exactly 126000 bytes), 25.4% (25.4 percent of whole disk size).

FORMAT

The format parameter of erase and partitioning (and RAID creation) is the filesystems name. You can determine this name by looking in /System/Library/Filesystems/<fs>.fs/Contents/Info.plistor by using the listFilesystems verb, which also lists shortcut aliases for common per- sonalities (these shortcuts are defined by diskutil for use with it only).
Some examples include: HFS+, HFS, JournaledHFS+, UFS, MS-DOS, etc.

Beginning with macOS El Capitan, system file permissions are automatically protected. It's no longer necessary to verify or repair permissions with Disk Utility (source).

If diskutil list returns one or more extra disks named: Apple UDIF read-only compressed (bzip2)
These are often old Adobe 'Flash Player' installers - they can be safely ejected using eject or with Disk Utility.

Diskutil replaces the disktool utility found in earlier versions of macOS. (disktool is now deprecated)

Examples

List all attached disks and partitions - device names and partition identifiers (equivalent to lsblk on unix):

$ diskutil list

/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *298.1 Gi disk0
1: EFI 200.0 Mi disk0s1
2: Apple_HFS Macintosh HD 297.8 Gi disk0s2

Get the Volume UUID (disk must already be mounted)

$ diskutil info disk0s2

Get the Volume ID of an IPOD

$ diskutil list |grep "IPOD" |grep -o '\(disk[0-9s]*\)'

Mount a disk using its Volume ID
$ diskutil mount Disk1

Mount a disk using its UUID
$ diskutil mount B172F107-06D4-39E3-9F7C-57466CD6489B

Erase a disk
$ diskutil eraseDisk UFS UntitledUFS disk3
$ diskutil eraseDisk JHFS+ Untitled disk3


Erase a volume
$ diskutil eraseVolume HFS+ UntitledHFS /Volumes/SomeDisk

Partition a disk

# Create 3 partitions:
# one partition as HFSX, one as JHFS+ and one as MS-DOS:
$ sudo diskutil partitionDisk disk3 3 HFSX Name1 10G JHFS+ Name2 10G MS-DOS NAME3 10G

Important: you cannot create non-HFS partitions on a disk if you intend to boot macOS on it.
Use these partitioning commands on a second (or third) disk that you mount after booting.

Resize a volume and create a volume after it, using all remaining space
$ diskutil resizeVolume /Volumes/SomeDisk 50g MS-DOS DOS 0b

Resize a volume and leave all remaining space as unused
$ diskutil resizeVolume /Volumes/SomeDisk 12g

Convert a disk to Core Storage and encrypt it
$ diskutil coreStorage convert disk3s2 -passphrase

Shrink your Core Storage PV in order to make space for a Boot Camp volume
subtract desired Windows size from LV size, to be new LV size, i.e. 150g
$ diskutil coreStorage list
$ diskutil coreStorage resizeStack LVUUID PVUUID 150g ms-dos BOOTCAMP 0


Revert a disk from Core Storage back to plain HFS, possibly decrypting
$ diskutil coreStorage revert disk5

Remove a partition diskutil eraseVolume Free\ Space not disk0s4

Merge two partitions into a new partition
$ diskutil mergePartitions JHFS+ not disk1s3 disk1s5

Split a partition into three new ones:
$ diskutil splitPartition /Volumes/SomeDisk JHFS+ vol1 12g MS-DOS VOL2 8g JHFS+ vol3 0b

Create a RAID
$ diskutil createRAID mirror MirroredVolume JHFS+ disk disk2

Destroy a RAID
$ diskutil destroyRAID /Volumes/MirroredVolume

Repair a damaged RAID
$ diskutil repairMirror /Volumes/MirroredVolume disk3

Convert volume into RAID volume
$ diskutil enableRAID mirror /Volumes/ExistingVolume

Erase a partition and shrink to add an associated Recovery Partition
$ diskutil splitPartition disk8s2 JHFS+ MacHD R %Apple_Boot% %noformat% %recovery%

“What you want, what you're hanging around in the world waiting for, is for something to occur to you” - Robert Frost

Related macOS commands:

asr - Apple Software Restore.
authopen(1).
bless - Set volume bootability and startup disk options.
drutil - Interact with CD/DVD burners.
Disk Utility (GUI) - The 'Info' button displays the disk identifier, UUID etc.
diskarbitrationd(8).
hdid(8).
hdiutil - Manipulate iso disk images.
hfs.util - HFS/HFS+ file system utility (Mount/unmount).
mount - Mount a file system.
ntfs.util - NTFS file system utility.
ufs.util - UFS file system utility (Mount/unmount).
SetFile(1) - Set extended attributes (Developer Tools).


 
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