Date: Sat, 02 Mar 2013 16:09:41 +0100 From: "Ronald Klop" <ronald-freebsd8@klop.yi.org> To: "Ben Morrow" <ben@morrow.me.uk>, "Daniel Eischen" <deischen@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: Re: Musings on ZFS Backup strategies Message-ID: <op.wtbq2fsm8527sy@pinky> In-Reply-To: <Pine.GSO.4.64.1303011521590.2804@sea.ntplx.net> References: <20130301165040.GA26251@anubis.morrow.me.uk> <20130301185912.GA27546@anubis.morrow.me.uk> <Pine.GSO.4.64.1303011521590.2804@sea.ntplx.net>
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On Fri, 01 Mar 2013 21:34:39 +0100, Daniel Eischen <deischen@freebsd.org> wrote: > On Fri, 1 Mar 2013, Ben Morrow wrote: > >> Quoth Daniel Eischen <deischen@freebsd.org>: >>> >>> Yes, we still use a couple of DLT autoloaders and have nightly >>> incrementals and weekly fulls. This is the problem I have with >>> converting to ZFS. Our typical recovery is when a user says >>> they need a directory or set of files from a week or two ago. >>> Using dump from tape, I can easily extract *just* the necessary >>> files. I don't need a second system to restore to, so that >>> I can then extract the file. >> >> As Karl said originally, you can do that with snapshots without having >> to go to your backups at all. With the right arrangements (symlinks to >> the .zfs/snapshot/* directories, or just setting the snapdir property to >> 'visible') you can make it so users can do this sort of restore >> themselves without having to go through you. > > It wasn't clear that snapshots were traversable as a normal > directory structure. I was thinking it was just a blob > that you had to roll back to in order to get anything out > of it. That is the main benefit of snapshots. :-) You can also very easily diff files between them. Mostly a lot of data is static so it does not cost a lot to keep snapshots. There are a lot of scripts online and in ports which make a nice retention policy like e.g. 7 daily snaphots, 8 weekly, 12 monthly, 2 yearly. See below for (an incomplete list of) what I keep about my homedir at home. > Under our current scheme, we would remove snapshots > after the next (weekly) full zfs send (nee dump), so > it wouldn't help unless we kept snapshots around a > lot longer. Why not. > Am I correct in assuming that one could: > > # zfs send -R snapshot | dd obs=10240 of=/dev/rst0 > > to archive it to tape instead of another [system:]drive? Yes, your are correct. The manual page about zfs send says: 'The format of the stream is committed. You will be able to receive your streams on future versions of ZFS.' Ronald. tank/home 115G 65.6G 53.6G /home tank/home@auto-2011-10-25_19.00.yearly 16.3G - 56.8G - tank/home@auto-2012-06-06_22.00.yearly 5.55G - 53.3G - tank/home@auto-2012-09-02_20.00.monthly 2.61G - 49.3G - tank/home@auto-2012-10-15_06.00.monthly 2.22G - 49.9G - tank/home@auto-2012-11-26_13.00.monthly 2.47G - 50.2G - tank/home@auto-2013-01-07_13.00.monthly 2.56G - 51.5G - tank/home@auto-2013-01-21_13.00.weekly 1.06G - 52.4G - tank/home@auto-2013-01-28_13.00.weekly 409M - 52.3G - tank/home@auto-2013-02-04_13.00.monthly 625M - 52.5G - tank/home@auto-2013-02-11_13.00.weekly 689M - 52.5G - tank/home@auto-2013-02-16_13.00.weekly 17.7M - 52.5G - tank/home@auto-2013-02-17_13.00.daily 17.7M - 52.5G - tank/home@auto-2013-02-18_13.00.daily 17.9M - 52.5G -
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