[OpenIndiana-discuss] Current ZFS Backup projects (OpenIndiana-discuss Digest, Vol 26, Issue 34) (OpenIndiana-discuss Digest, Vol 26, Issue 39)
ong.yu.phing at group.ong-ong.com
Fri Sep 14 06:51:40 UTC 2012
Yes, there are two slightly different goals in terms of backup, (1) to
backup ZFS based CIFS servers (2) to backup non-ZFS based servers. For
(1) I've been trying to use tools like zetaback, warmer, etc. For (2)
I've been using good-ol' backuppc.
I'm quite glad this thread started, because lo and behold we now have
zrep pointed out by Frank (written by Philip Brown, according to the
website), which looks exactly like what I'm interested in for (1), and
mdbackup from Julius, which looks like I could use for (2), although I
might still stay with backuppc as my staff are quite familiar with this.
So thanks all for your valuable inputs!
On 13/09/2012 17:23, Jim Klimov wrote:
> 2012-09-12 6:05, Ong Yu-Phing ?????:
>> Jim, I assume you are referring to this:
> Yes, I think that's it ;)
>> My concern is that typically rsync will take quite a while to traverse a
>> large set of files before sending only changed files; a classic example
>> is backing up say 1TB of maildir emails, it may take 4+ hours, and you
>> now have to deal with a situation where your midnight backup is really a
>> "somewhere between midnight and 4am" backup. And of course, if you want
>> to take snapshots/backups of comstar volumes, rsync isn't quite the
>> right fit.
>> On the other hand, a zfs snapshot gives an almost-at-the-time backup
>> (give or take a few seconds), versus the aforementioned rsync. The zfs
>> snapshot can then be sent off-site, independent of the backup activity.
> I got an impression that you needed to backup some "client" machines
> with varied OSes, such as Windows or Linux desktops, onto a ZFS server.
> In that case rsync should help, although you're right that it would
> take long to scan the directory trees for changes.
> With client FSes that support snapshots (ZFS, NTFS shadow copy) you
> might have some luck making scripts that take the client's snapshot,
> hold it (in case of ZFS, to avoid it being destroyed while you're
> working), rsync the changes from the snapshot (so the 0am backup is
> really the state at 0am) and release/destroy the snapshot on client.
> In case of ZFS at least, you might have some optimization by using
> "zfs diff" to determine changed files between two snapshots on the
> client - but then you should not destroy rsynced snapshots right
> away, but keep a backlog of one or two at least. And you should have
> some locking to prevent several instances of the backup job crawling
> the same client space and bringing IOPS to a halt.
> Now, before you ask "why not zfs-send client snapshots directly?" -
> there may be reasons, such as incompatible ZFS versions on client
> and server, differing dataset layouts, flaky network preventing
> transfer of large zfs-send streams (though that should have been
> addressed with resumable zfs-send feature, if that was integrated).
> //Jim Klimov
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