Re: OK to take hourly snapshots, then cull older ones?

[Roman Mamedov <rm@romanrm.net>]

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On Mon, 14 Oct 2013 21:05:33 -0700
David Madden <dhm@mersenne.com> wrote:

> I'd like to use BTRFS to do something like the old NetApp snapshot
> system: every hour or so, there'd be a snapshot, then the 23 of the
> snapshots during a day would be deleted, leaving just a day snapshot,
> then after a month, 6 of 7 snapshots would be deleted, leaving just a
> week snapshot, and so on.
> 
> Is this a reasonable thing to do in a cron job with a BTRFS filesystem?
>  Apart from running out of space, are there any resources that might get
> used up?  Has anybody done this for a year or two in an active
> filesystem, and encountered success or weirdness?

Sure, that's one of the more awesome uses of btrfs.

But keep in mind that old snapshots on the same FS are not to be used instead
of a proper backup to external media/servers. If a block happened not to
change for a year, and it gets damaged on disk, it will become damaged in all
the snapshots all the way back to a year ago, and you lose that data.

-- 
With respect,
Roman

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