On Tuesday 09 March 2010 07:55:38 datenritter wrote:
> By the way: This makes me worry. Dirvish does not automatically create
> "original" backups on a regular basis. So if you shred a file or lose it
> to a physical disc error, all those additional hardlinks won't help.

You're right: If you modify a backed-up file in one of your vaults (using a 
program that modifies the file in place rather than creating a new file the 
save 
the new contents in), it will modify all the other backed-up files with the 
same hardlink. Your backups should be read-only for this reason. Of course, 
having them read-only won't protect against disk error.

> I think you'd have to re-init the vault from time to time or maybe
> create a second (and a third...) vault with the same config to double
> the files. Or backup the backups, or create filesystem-mirrors, or...?

Rotating backups seems to be a common technique and probably a good idea if 
you need to protect the snapshots against disk error. Just periodically copy 
the entire HD that use store your vaults on to another disk or to tape. If you 
are concerned about partial-disk error like bad sectors, then you could also 
store a checksum of each file (or disk sector/block?) so that if the contents 
of your backup and your backup-backup differ, you know which one is right.

All this depends on what risks you are trying to protect against. For my 
personal files I am fine with just having the vault on a different disk than 
the 
original data. Sure, if my backup disk dies, I lose the snapshots... but my 
main goal is to make sure I don't lose my current data. The snapshots are just 
a nice bonus.

-Andy Feldman

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