Apple Mac OS X Server manual Using asr to Restore System Images

To split an image into three segments:

$ hdiutil segment -segmentSize 10m -o /tmp/aseg 30m.dmg

This creates three separate files: aseg.dmg, aseg.002.dmgpart, and aseg.003.dmgpart.

To convert an image to a CD-R export image with a .toast extention:

$ hdiutil convert master.dmg -format UDTO -o master

To burn an image onto the CD drive:

$ hdiutil burn myImage.dmg

To create an image from a folder:

$ hdiutil create -srcfolder mydir mydir.dmg

Using asr to Restore System Images

The asr tool can efficiently copy disk images onto volumes. asr can also accurately clone volumes.

To clone a volume:

$ sudo asr -source /Volumes/Classic -target /Volumes/install

To restore an system image onto a volume:

$ sudo asr -source compressedimage -target <targetvol> -erase

Note: The target drive will be erased.

Imaging Multiple Clients Using Multicast asr

You can enable a multicast image server using Mac OS X Server. Multicast asr can restore multiple clients simultaneously from one looping multicast of an asr disk image. Each client can start receiving the restore image at any time during a multicast of the image, and the client continues receiving the first part of the next multicast until the client has received the complete restore image. The server multicasts only one copy of the restore image at a time, and all clients receive this copy.

If the server finishes multicasting the restore image and a client is still requesting the image, the server multicasts the image again. Thus, using multicast asr to stream images to multiple clients doesn’t congest the network nearly as much as Network Install with multiple clients. Use the asr tool with the -serverflag and a correctly built image and plist to enable the image server.

To start up a multicast server for a specified image:

$ asr -source <compressedimage> -server <configuration.plist>

where the specified image used the parameters in the configuration.plist file. 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.

Chapter 11 Working with NetBoot Service and System Images

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