From owner-freebsd-fs@FreeBSD.ORG Thu Nov 13 04:34:16 2008 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4968C1065673 for ; Thu, 13 Nov 2008 04:34:16 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from QMTA02.emeryville.ca.mail.comcast.net (qmta02.emeryville.ca.mail.comcast.net [76.96.30.24]) by mx1.freebsd.org (Postfix) with ESMTP id 1DD308FC0C for ; Thu, 13 Nov 2008 04:34:15 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from OMTA10.emeryville.ca.mail.comcast.net ([76.96.30.28]) by QMTA02.emeryville.ca.mail.comcast.net with comcast id eS2e1a0010cQ2SLA2UaFgN; Thu, 13 Nov 2008 04:34:15 +0000 Received: from koitsu.dyndns.org ([69.181.141.110]) by OMTA10.emeryville.ca.mail.comcast.net with comcast id eUaE1a0052P6wsM8WUaEtv; Thu, 13 Nov 2008 04:34:15 +0000 X-Authority-Analysis: v=1.0 c=1 a=6I5d2MoRAAAA:8 a=QycZ5dHgAAAA:8 a=FiroYRd1fLxy0W-RoiUA:9 a=fh9Iusfim94nvvmBvZFVl2gO1OkA:4 a=EoioJ0NPDVgA:10 a=LY0hPdMaydYA:10 Received: by icarus.home.lan (Postfix, from userid 1000) id 16DBB5C19; Wed, 12 Nov 2008 20:34:14 -0800 (PST) Date: Wed, 12 Nov 2008 20:34:14 -0800 From: Jeremy Chadwick To: Kevin Day Message-ID: <20081113043414.GA10272@icarus.home.lan> References: <6EEFB17C-10DF-4CCD-AB07-83B4B75D033F@dragondata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6EEFB17C-10DF-4CCD-AB07-83B4B75D033F@dragondata.com> User-Agent: Mutt/1.5.18 (2008-05-17) Cc: freebsd-fs@freebsd.org Subject: Re: UFS Snapshot lock time X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Nov 2008 04:34:16 -0000 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 |