Xserve Cluster Setup
To image the Xserve cluster nodes we created a custom startup item that was installed on a bootable CD located at /Library/StartupItems/NodeImager. At bootup the startup item is executed and proceeds to image the host node's hard drive from a compressed image on the same external firewire disk using the Apple Software Restore utility, asr.


NodeImager Startup Item

The NodeImager startup item is a simple shell script that runs asr (with optional log output asr_log.txt) and reboot command. The script is shown here:

 
#!/bin/sh
/usr/sbin/asr -source /Volumes/Image/Server\ HD.dmg \
              -target /Volumes/Server\ HD           \
              -erase                                \
              -noprompt > asr_log.txt &
wait
sleep 30 &
wait
/sbin/reboot
NodeImager Startup Parameters

The other piece of the startup item is the StartupParameters.plist file dislayed below:

 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>Description</key>
        <string>GeoCenter Xserve Cluster Node Imager</string>
        <key>Messages</key>
        <dict>
                <key>start</key>
                <string>Imaging System</string>
        </dict>
        <key>OrderPreference</key>
        <string>Last</string>
        <key>Provides</key>
        <array>
                <string>New System Image</string>
        </array>
        <key>Requires</key>
        <array>
                <string>Disks</string>
        </array>
</dict>
</plist>
Sample `asr` Log

 
Validating target...done
Validating source...done
Erasing target device /dev/disk0s3...done
Retrieving scan information...done
Validating sizes...done
Restoring  ....10....20....30....40....50....60....70....80....90....100
Verifying  ....10....20....30....40....50....60....70....80....90....100
Remounting target volume...done
Next -> Node Config Script