From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id F25347F37 for ; Sun, 23 Jun 2013 18:39:36 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay1.corp.sgi.com (Postfix) with ESMTP id CBF428F8035 for ; Sun, 23 Jun 2013 16:39:36 -0700 (PDT) Received: from ipmail06.adl6.internode.on.net (ipmail06.adl6.internode.on.net [150.101.137.145]) by cuda.sgi.com with ESMTP id 4Nx4xL8SeVLcJocd for ; Sun, 23 Jun 2013 16:39:35 -0700 (PDT) Date: Mon, 24 Jun 2013 09:39:33 +1000 From: Dave Chinner Subject: Re: LVM + XFS + external log + snapshots Message-ID: <20130623233933.GF29376@dastard> References: <022467CC-8EB2-41E9-8AF6-46F781882F6B@gmail.com> <20130623225546.GB29376@dastard> <51C783B7.2040502@sandeen.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <51C783B7.2040502@sandeen.net> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: xfs@oss.sgi.com, aurfalien On Sun, Jun 23, 2013 at 06:24:39PM -0500, Eric Sandeen wrote: > On 6/23/13 5:55 PM, Dave Chinner wrote: > > On Fri, Jun 21, 2013 at 10:30:31PM -0700, aurfalien wrote: > >> Hi all, > >> > >> So I have an XFS file system within LVM which has an external log. > >> > >> My mount option in FSTAB is; > >> > >> /dev/vg_spock_data/lv_data /data xfs logdev=/dev/sdc1,nobarrier,logbufs=8,noatime,nodiratime 1 1 > >> > >> All is well no issues and very fast. > >> > >> Now I'd like to snapshot this bad boy and then run rsnapshot to create a few days backup. > > > > You need to snapshot the log device as well. > > > > But that is problematic in that you need to snapshot it at the same > > time you snapshot the data volume. Hence yo'd have to do: > > > > # xfs_freeze -f > > # > > # > > # xfs_freeze -u > > > > And now you can mount the snapshot with: > > > > # mount /dev/vg_spock_data/datasnapshot /snapshot -o nouuid,ro,logdev=/dev/vg_spock_log/logsnapshot > > > > If you can't snapshot the log device, then you can't snapshot the > > filesystem. Yet another reason for using internal logs... > > Hm, given that freezing the fs makes the log (almost) completely clean, I wonder > if he could mount with /dev/zero (or a loopback 0-filled file) to get at the snapshot, > especially since it's being mounted RO. > > Should be safe & consistent, no? In theory. Never tried it myself. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs