This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-users] A simple backup

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] A simple backup
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Fri, 9 May 2008 09:12:14 +0100
Cc: "Fajar A. Nugraha" <fajar@xxxxxxxxx>, Nick Anderson <nick@xxxxxxxxxxxx>, Steve Spencer <sspencer@xxxxxxxx>
Delivery-date: Fri, 09 May 2008 01:08:48 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <4823E2CB.7060307@xxxxxxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <48221AEF.50009@xxxxxxxx> <4823AA96.1040904@xxxxxxxxx> <4823E2CB.7060307@xxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: KMail/1.8.2
> > IMHO, even the best commercial SAN-based backup solution uses that
> > assumption, so for practical purposes, atomic backup for domU's storage
> > should be sufficient.
> So are local logical volume snapshots atomic? I could see a network
> block device not being quite atomic with lv snapshot, but it seems that
> local storage on lv should be atomic. I keep reading conflicting data
> about weather it is or is not atomic.

Local LVM snapshots are atomic, I think.  It's just that atomicity of a 
snapshot is not sufficient to guarantee that the snapshot is *consistent*, 
due to caching in the guest.  Yanking the power cord out of the machine 
creates a consistent snapshot of its current disk state (by atomically 
preventing the machine updating its disk ;-)) but that will also need a 
filesystem recovery before the FS is actually readable.


Xen-users mailing list

<Prev in Thread] Current Thread [Next in Thread>