rahvee
Joined: 21 Feb 2010
Posts: 1
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 Posted: Sun Feb 21, 2010 8:00 pm Post subject: Incrementally backing up sparse files ... VMs and TrueCrypt |
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Does nobody do incremental backups of sparse files? I can’t believe there’s no good way to do it. Of particular interest, I would like to backup daily:
<![if !supportLists]>· <![endif]>TrueCrypt sparse files in Windows (Truecrypt calls this “Dynamic.”)
<![if !supportLists]>· <![endif]>Virtualbox, or VMWare Workstation sparse (“expanding”) virtual disks in windows
<![if !supportLists]>· <![endif]>VMWare Fusion or Parallels sparse virtual disks in Mac
I would like to back these up frequently, and efficiently. If I have a 50G container file that occupies 20G on disk, the initial backup should be close to 20G, and when I modify 1M in the middle of the file and then save, I don’t want the incremental backup trying to send either 20G or 50G again.
On the mac, the Sparsebundle concept solves this problem. It’s just like a truecrypt image, but it’s broken up into a whole bunch of little 8M chunks. So when I modify 1M in the middle of the volume and save, my next backup will send one updated 8M chunk for backup. A little bit of waste, but well within reason.
I currently have Virtual Machines and TrueCrypt images excluded from the regular Time Machine and Acronis True Image backups of peoples’ laptops. But I’m not comfortable simply neglecting the VM’s and TrueCrypt volumes, as if they’re not important.
I haven’t found anything satisfactory yet. The closest I found so far was Crashplan. It does “byte pattern differential” and “continuous real-time backup,” which means it can detect blocks changing in the middle of a file, and only send the changed blocks of a sparse file during incrementals, instead of sending the whole 50G again. Unfortunately, crashplan can’t restore a sparse file. D’oh!!!  Actually, that’s a fib. It can restore sparse files, but they won’t be sparse anymore. So … IMHO … that’s not useful. I am conversing with their support, but don’t know the results yet of that effort.
I’ve also tried rsync, and tar. People all over the place say it should do well, but in practice, so far I find they’re only good for a one-time Full backup. Not good at incrementals.
Anybody doing anything they’re happy with, to backup sparse files on a regular basis, quickly, efficiently, frequently?
Thanks… |
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