Imaging live server

[cmcfarling]

Newer versions of Symantec Ghost have a “hot imaging” feature that allow you to image the startup drive of a Windows machine while it’s up and running. I’d like to be able to do something similar with OSX server.

First off, can hdiutil image a startup disk that’s in use? I’d also like to be able to make incemental updates once the initial disk image is created.

I’m curious to hear what strategies others are using to accomplish this type of thing.

[cmcfarling]

From what I can gather Ghost has the ability to backup open files. I assume it uses technology similar to Acronis Trueimage for which I dug up a whitepaper on the internet. Basically it incorporates a driver that sits above the disk driver and can intercept writes while the app is imaging.

Ideally I’d like to be able to backup an OSX server startup disk to a dmg file stored elsewhere on the network for disaster recover purposes. When needed I could simply use asr to restore the dmg to the server drive and be up & running quickly.

So far there are several caveats that I’m running into. The volume where the backups will go is an SMB volume on a Windows server. The machines I want to do this on are currently running 10.3.9. In all my testing, I can’t get hdiutil to store a -srcfolder dmg file on an SMB share. I’m beginning to think that the 10.3.9 hdiutil simply can’t accomplish this (it does work with 10.4 though).

Another option would be to forget the dmg and use rsyncx. Again the fact the the destination is an SMB share presents complications that I’d rather not mess with with regard to resouce forks. Even if I got this working, restoring to a new disk wouldn’t be as simple as the asr method.

A third option would be to use a combination of a dmg file and rsyncx. I realize upgrading to 10.4 (or even 10.5 when it’s available) would simplify matters and it may just be time to finally do that. For the initial backup, hdiutil could be used to image the startup disk and store it on a remote volume. Then, periodically rsyncx (or rsync if using 10.4 or later) could be used to syncronize changes between the startup disk and the dmg file. This would maintain an up-to-date dmg file while still allowing a fast restore with asr.

Is anyone running this type of backup operation? Is there any reason why this wouldn’t work well?

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