Apple Software Restore; copy volumes (e.g. from disk images.)

     asr verb [options]
     asr restore --source source --target target [options]
     asr server --source source --config configuration [options]
     asr restore --source asr://source --file file [options]
     asr imagescan --source image [options]
     asr help | version

asr efficiently copies disk images onto volumes, either directly or via a multicast network stream.
asr can also accurately clone volumes without the use of an intermediate disk image.

In its first form, asr copies source (usually a disk image, potentially on an HTTP server) to target.
source can be specified using a path in the filesystem, or an http or https URL. It can also be an asr:// URL to indicate a multicast source. asr can also be invoked with its second form to act as a multicast server. In its third form, asr will restore a multicast disk image to a file instead of disk volume. In its fourth form, asr prepares a disk image to be restored efficiently, adding whole-volume checksum information. help and version provide usage and version information, respectively.

source and target can be /dev entries or volume mountpoints. If restoring a multicast disk image to a file, file can be a path to a local file or directory. If the specified path is a file, the disk image is given the specified name. If a directory, the name of the disk image being multicast is used. When specifying server, source has to be a UDIF disk image. Restoring from a multicast stream is accomplished by passing a asr:// url as source.

When run in its first form above, the --erase option must always be used, as asr no longer supports file copying. Such functionality is done better by ditto.

asr needs to be run as root (see sudo) in order to accomplish its tasks.

     Each verb is listed with its description and individual arguments.

     restore    restores a disk image or volume to another volume (including a mounted disk image)

                --source       can be a disk image, /dev entry, or volume mountpoint. In the latter two
                               cases, the volume must be unmountable or mounted read-only in order for a
                               erase blockcopy to occur (thus, one cannot erase blockcopy the root filesystem
                               as the source, unless it happened to be mounted read-only).

                --target       can be a /dev entry, or volume mountpoint. Must be unmountable in order for
                               an erase block-copy to occur.

                --file         when performing a multicast restore, --file can be specified instead of
                               --target. If the specified path is a file, the disk image is given the specified
                               name. If a directory, the name of the disk image being multicast is

                --erase        erases target and is required.  --erase must always be used, as file copies
                               are no longer supported by asr.  If source is a asr:// url for restoring from
                               a multicast stream, --erase must be passed (multicasting only supports erase
                               block-copy restores).  Passing --erase with --file indicates any existing
                               file should be overwritten when doing a multicast file copy.

                --format HFS+ | HFSX
                               specifies the destination filesystem format, when --erase is also given. If
                               not specified, the destination will be formatted with the same filesystem
                               format as the source. If multicasting, the --format specified must be block
                               copy compatible with the source.  --format is ignored if --erase is not used.
                               Note: HFS Journaling is an attribute of the source image, and is not affected
                               by --format.

                --noprompt     suppresses the prompt which usually occurs before target is erased.
                               newfs_hfs(8) will be called on target and once you start writing new data,
                               there isn't much hope for recovery.  You have been warned.

                --timeout num  specifies num seconds that a multicast client should wait when no payload
                               data has been received over a multicast stream before exiting, allowing the
                               client to stop in case of server failure/stoppage.  It defaults to 0 (e.g.
                               never time out).

                               provide progress output that is easy for another program to parse.  Any program
                               trying to interpret asr's progress should use --puppetstrings.

                --noverify     skips the verification steps normally taken to ensure that a volume has been
                               properly restored.  --noverify allows images which have not been scanned to
                               be restored.  Skipping verification is dangerous for a number of reasons and
                               should never be used in production systems.

                               allows restores to proceed even if the source's catalog file is fragmented
                               (in particular, if it has more than 8 extents).  By default such restores are
                               disallowed.  Catalog fragmentation is undesirable and in most cases it is
                               better to fix the problem on the source (e.g. by running fsck_hfs -r on it),
                               but --allowfragmentedcatalog is provided for situations where such a change
                               is impractical.

     server     multicasts source over the network. Requires --erase be passed in by clients (multicasting
                only supports erase block-copy restores).

                --source   source has to be a UDIF disk image. A path to a disk image on a local/remote volume
                           can be passed in, or a http:// url to a disk image that is accessible via a
                           web server.

                           the network interface to be used for multicasting (e.g. en0) instead of the
                           default network interface.

                --config   server requires a configuration file to be passed, in standard property list format.
                           The following keys/options configure the various parameters for multicast


                Data Rate              this is the desired data rate in bytes per second.  On average, the
                                       stream will go slightly slower than this speed, but will never exceed
                                       it.  It's a number in the plist (-int when set with defaults(1)).

                                       Note: The performance/reliability of the networking infrastructure
                                       being multicast on is an important factor in determining what data
                                       rate can be supported. Excessive/bursty packet loss for a given data
                                       rate could be due to an inability of the server/client to be able to
                                       send/receive multicast data at that rate, but it's equally important
                                       to verify that the network infrastructure can support multicasting at
                                       the requested rate.

                Multicast Address      this is the Multicast address for the data stream. It's a string in
                                       the plist.


                Client Data Rate       this is the rate the slowest client can write data to its target in
                                       bytes per second.  if asr misses data on the first pass (x's during
                                       progress) and slowing the Data Rate doesn't resolve it, setting the
                                       Client Data Rate will dynamically regulate the speed of the multicast
                                       stream to allow clients more time to write the data. It's a number in
                                       the plist (-int when set with defaults(1)).

                DNS Service Discovery  whether the server should be advertised via DNS Service Discovery,
                                       a.k.a. Bonjour (tm).  It defaults to true.  It's a boolean in the
                                       plist (-bool when set with defaults(1)).

                Loop Suspend           a limit of the number of times to multicast the image file when no
                                       clients have started a restore operation. Once exceeded, the server
                                       will stop the stream and wait for new clients before multicasting the
                                       image file. It defaults to 0 (e.g. never stop multicasting once a
                                       client starts the stream), and should not be set to <2.  It’s a
                                       number in the plist (-int when set with defaults(1)).

                Multicast TTL          the time to live on the multicast packets (for multicasting through
                                       routers). It defaults to 3.  It cannot be set to 0, and should not be
                                       set to 1 (otherwise, it could adversely affect some network routers).
                                       It's a number in the plist (-int when set with defaults(1)).

                Port                   the port of initial client-server handshake, version checks, multicast
                                       restore metadata, and stream data.  It defaults to 7800.  This
                                       should only be included/modified if the default port cannot be used.
                                       It's a number in the plist (-int when set with defaults(1)).

     imagescan  calculate checksums of the data in the provided image and store them in the image.  These
                checksums are used to ensure proper restores.  Also determines if the disk image is in order
                for multicasting, and rewrites the file in order if not.  If the image has to be reordered,
                it will require free disk space equal to the size of the disk image being scanned.

                          bypasses the check/reordering of a disk image file for multicasting. By default
                          disk images will be rewritten in a way that's necessary for multicasting.

                          bypasses the check for a fragmented catalog file.  By default that check is done
                          and scanning won't be allowed on an image that has a fragmented catalog file.  It
                          is usually a better idea to fix the image (e.g. run fsck_hfs -r on a writable copy
                          of it) than to use --allowfragmentedcatalog, but it is provided in case fixing the
                          image is impractical.


The following options control how asr uses memory. These options can have a significant impact on performance.
asr is optimized for copying between devices (different disk drives, from a network volume to a local disk, etc). As such, asr defaults to using eight one megabyte buffers. These buffers are wired down (occupying physical memory). For partition to partition copies on the same device, one large buffer (e.g. 32 MB) is much faster than the default eight medium sized ones. For multicast, 4 256k buffers are the default. Custom buffering for multicast operation is not recommended.

     --csumbuffers and --csumbuffersize allow a different buffer configuration for checksumming operations.
     One checksum buffer offers the best performance.  The default is 1 1MB buffer. Custom checksum buffering
     is not recommended.

     Like mkfile(8), size defaults to bytes but can be followed by a multiplier character (e.g. 'm').

     --buffers num
                 specifies that num buffers should be used.

     --buffersize size
                 specifies the size of each buffer.

     --csumbuffers num
                 specifies that num buffers should be used for checksumming operations (which only affect
                 the target).  Custom checksum buffering is not recommended.

     --csumbuffersize size
                 specifies the size of each buffer used for checksumming.  Custom checksum buffering is not

     --verbose   enables verbose progress and error messages.
     --debug     enables other progress and error messages.

     Volume cloning:
           sudo asr restore --source /Volumes/Classic --target /Volumes/install --erase

           sudo asr restore -s compressedimage -t targetvol --erase

     Will erase the target and potentially do a block copy restore.

     Multicast server:
           asr server --source compressedimage --config configuration.plist

     Will start up a multicast server for the specified image, using the parameters in the configura-tion.plist.
     The image will not start multicasting on the network until a client attempts to start a
     restore. The server will continue to multicast the image until the process is terminated.

     An example multicast configuration file:
           defaults write /tmp/streamconfig "Data Rate" -int 6000000
           defaults write /tmp/streamconfig "Multicast Address" mcastaddr
           (will create the file /tmp/streamconfig.plist)
           mcastaddr should be appropriate for your network infrastructure and policy, usually from a
           range assigned by your network administrator.

     Multicast client
           sudo asr restore --source asr://hostname --target targetvol --erase

     Multicast client restoring to a file
           sudo asr restore --source asr://hostname --file file --erase
     Will receive the multicast stream from hostname and save it to a file. If  is a directory, the
     image of the streamed disk image will be used the save the file. --erase causes any existing file with
     the same name to be overwritten.

asr requires a properly created disk image for most efficient operation. This image is most easily made with the Disk Utility application's "Image from Folder" function in macOS 10.3. The Disk Copy from macOS 10.2.3 (v55.6) or later can also be used.

     Basic steps for imaging and restoring a volume:

     1.   Set up the source volume the way you want it.

     2.   Use Disk Utility's "Images -> New -> Image from Folder..." function and select the root of the
          volume.  Save the image as read-only or compressed.  "Images | New | Image from device" is not
          recommended on 10.3.x.

     3.   Scan the image with "Images -> Scan Image for Restore."

     4.   Select an image or volume and click on the "Restore" tab.  Drag the source image and destination
          partition to the source and destination fields.  Click Restore.


asr can block copy restore HFS+/HFSX filesystems and resize the source filesystem to fit in the target's partition if the source filesystem data blocks will fit within the target partition's space (resizing the filesystem geometry as appropriate).

HFS+ can be used as the source of a block copy to either an HFS+ or HFSX destination. However, an HFSX source can only be used to block copy to an HFSX destination. This is because case collision of file names could occur when converting from an HFSX filesystem to HFS+.

Certain non-HFS+/HFSX filesystems will block copy restore, but the target partition will be resized to match the size of the source image/partition size, with no filesystem resizing occurring.

     asr maintains compatibility with previous syntax, e.g.

     asr -source source -target target [options]
     asr -source source -server configuration [options]
     asr -source asr://source -file file [options]
     asr -imagescan [options] image
     asr -h | -v

     where -source, -target, and -file are equivalent to --source, --target, and --file respectively, and
     all [options] are equivalent to their -- descriptions.  asr -server configuration is superseded by asr
     server --config configuration.  The following deprecated options also remain:

     -nocheck   this option is deprecated, but remains for script compatibility.  Use -noverify instead.

                this option is deprecated, but remains for script compatibility. On by default.  Note that
                if an image scanned with -blockonly cannot be block-copied to a particular target an error
                will occur, since the file-copy information was omitted.

     Note: Compatibility with previous syntax is not guaranteed in the next major OS release.


asr will exit with status 1 if it cannot complete the requested operation. A human readable error mes-sage message sage will be printed in most cases. If asr has already started writing to the target volume when the error occurs, then it will erase the target, leaving it in a valid (but empty) state. It will, how-ever, however, ever, leave it unmounted.

Some of the error messages which asr prints are generated by the underlying subsystems that it uses, and their meaning is not always obvious. Here are some useful guidelines:

     1.   asr does some preflight testing before it starts actually copying data.  Errors that show up dur-ing during
          ing this preflighting are usually clear (e.g. "There is not enough space in volume "Macintosh HD"
          to do the restore.")

     2.   If an error occurs during the copy, it might be because there is corruption in the source image
          file.  Try running "hdiutil verify" with the image.  A common error message which indicates this
          is "codec overrun".

     3.   Errors which occur during the copy and which don't have an obvious cause (i.e. the error message
          is difficult to interpret) might be transient in nature (e.g. there was an I/O error on the disk),
          and it is worth trying the restore again.

Apple Software Restore got its start as a field service restoration tool used to reconfigure computers' software to 'factory' state. It later became a more general software restore mechanism and software installation helper application for various Apple computer products. ASR has been used in manufacturing processes and in shipping computers' System Software Installers.

For macOS, asr was rewritten as a command line tool for manufacturing and professional customers.
asr is the backend for the macOS Software Restore application that shipped on Macintosh computers as well as the Scan and Restore functionality in Disk Utility.

Multicast support was added to allow multiple clients to erase restore an image from a multicast net-work network
work stream. Per its history, most functionality in asr is limited to HFS+ volumes.

“They always say time changes things, but you actually have to change them yourself” ~ Andy Warhol

Related macOS commands

Local man page: asr - Command line help page on your local machine.
bless - Set volume bootability and startup disk options.
ditto - Copy files and folders.
df - Display free disk space.
hdiutil - Manipulate iso disk images.
what - show what versions of object modules were used to construct a file.

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