svn hotcopy vs. LVM snapshot

From: Phil Endecott <spam_from_subversion_users_at_chezphil.org>
Date: 2005-11-22 17:07:00 CET

('binary' encoding is not supported, stored as-is) Dear List,

Has anyone investigated the relative merits of "svn hotcopy" and LVM snapshots?

If you haven't heard of LVM snapshots - which I hadn't until yesterday - they provide a machanism to take an atomic snapshot of a filesystem at the block-level, e.g. something like

lvcreate --snapshot --name snap /path/to/device
mount snap /mnt/snap

/mnt/snap will now be a read-only snapshot of the state of the filesystem when the snapshot was taken, which you can backup without worrying about things changing simultaneously. You can back up using tar on the mounted snapshot or dump on the unmounted snapshot device.

To some extent the use of snapshots makes things like svn hotcopy, database dump programs, and so on, redundant. From the administrator's point of view it means that they no longer need to worry about the "magic runes" needed for each type of data being backed up.

On the other hand it does rely on a point-in-time snapshot of the filesystem being something from which you can recover. I believe that this is true of Subversion; am I right? Has anyone else already looked into this?

Regards,

--Phil.

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Received on Tue Nov 22 16:50:38 2005