Date: Wed, 12 Nov 2008 20:34:14 -0800 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Kevin Day <toasty@dragondata.com> Cc: freebsd-fs@freebsd.org Subject: Re: UFS Snapshot lock time Message-ID: <20081113043414.GA10272@icarus.home.lan> In-Reply-To: <6EEFB17C-10DF-4CCD-AB07-83B4B75D033F@dragondata.com> References: <6EEFB17C-10DF-4CCD-AB07-83B4B75D033F@dragondata.com>
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On Wed, Nov 12, 2008 at 08:22:29PM -0600, Kevin Day wrote: > Is there any documentation out there that explains how to optimize UFS > snapshotting? > > Specifically, we've got a rather big filesystem that I'd like to do > hourly snapshots of. I don't mind how long the snapshot itself takes, > but the amount of time the filesystem is locked is a problem. We're > "dead" for about 12 minutes per snapshotting. This topic comes up about once every 2 weeks. There's a discussion going about it on -stable right now: http://lists.freebsd.org/pipermail/freebsd-stable/2008-November/046524.html It's also been documented on my issues Wiki: http://wiki.freebsd.org/JeremyChadwick/Commonly_reported_issues At this time, there is no fix. Workarounds: 1) Use rsnapshot (which is rsync-based) to accomplish the same; this works on a UFS/UFS2 filesystem. However, note that file atimes on your source will get destroyed (which will affect the "new mail" capability of classic UNIX mboxes; there is no solution for that) 1) Switch to ZFS, which has a reliable snapshotting. > In theory, this should be a rather fast box, but it is a rather large > filesystem. The speed of the box has nothing to do with the problem; your hardware is not to blame. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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