If you’ve arrived here looking to use iSCSI with Time Machine, I’ve switched to another more robust method. I’ve run into some of the same problems as commenters below, and I’ve become convinced the iSCSI angle is too risky for now.
Open a terminal and run:
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
Then you can use a Samba or AppleShare (even Netatalk) server share as a time machine backup location. This works perfectly, as Time Machine creates a disk image with an HFS+ filesystem on which to perform backups, and mounts that.
I’ll leave the original post here for those interested.
Got Leopard? Too cheap/lazy to go get a USB drive for backups? Like taking risks? Etc.
One of the things I was looking forward to in MacOS X 10.5 was Time Machine. To my knowledge, Time Machine was to support two ways of backing up – to a locally connected hard drive, or to a hard drive connected to an AirPort base station. I figured I’d mix it up a little and try centralizing my backup storage to my Linux servers. To do this, I employed iSCSI to connect storage space on the Linux server to the Mac. iSCSI accomplishes this in such a way that MacOS (and any other iSCSI client) sees the disk as a locally connected SCSI disk, and therefore it passes the criteria for Time Machine. You even format it as HFS+ in the normal way when a new disk is connected.
If you have a fileserver capable of delivering iSCSI LUNs, (and if you don’t know what iSCSI LUNs are, go get a USB drive), you can use the globalSAN iSCSI Initiator for OS X to do this with Leopard. They don’t specifically mention compatibility with Leopard, but this has been working for me for several hours now as of the time of this writing.
Caveat emptor: I did hard lock the iMac during a first attempt at an initial backup, but it’s hard to say whether it was iSCSI or one of the myriad other things I was doing at the time. Factor in Leopard being brand spankin’ new, and I can’t say for sure what caused it. If you have a sense of adventure, try this out.