[sclug] Snapshot disk images

John Stumbles sclug at yaph.org.uk
Wed Jul 27 08:29:31 UTC 2011

On 27/07/11 06:58, Darren Davison wrote:
> On Wed, 27 Jul 2011 00:17:26 +0100
> John Stumbles<sclug at yaph.org.uk>  wrote:
>> But of course that's another 10G for each snapshot
>> whereas an intelligent system would only add space taken by the
>> differences. I guess a suitable bit of rsync magic might do that for
>> me, but wondered if there is something already rolled.
> rsnapshot?

I think that makes snapshots of a filesystem at the level of directory 
trees rather than disk images, and if you were making multiple disk 
images it would treat them as different files and store them separately 
thus not saving you any space.

But rsync can analyse files and sync them by just transferring missing 
or differing blocks. IIRC it can write a schedule of diffs to sync 
filesystems that you can e.g. put on removable media and transfer via 
sneakernet, so should be possible to store just the first dd-type disk 
image and subsequent diffs. I think virtualbox does something similar to 
save snapshots of its guest OS images.

John Stumbles                                       http://yaph.org.uk

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