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] Re: cLVM on Debian/Lenny

To: Jan Kalcic <jandot@xxxxxxxxxxxxxx>
Subject: Re: [Xen-users] Re: cLVM on Debian/Lenny
From: Javier Guerra <javier@xxxxxxxxxxx>
Date: Mon, 20 Apr 2009 13:29:55 -0500
Cc: Thiago Camargo Martins Cordeiro <thiagocmartinsc@xxxxxxxxx>, Olivier Le Cam <Olivier.LeCam@xxxxxxxxxxxxxxxxxxxxx>, Ferenc Wagner <wferi@xxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx, John Madden <jmadden@xxxxxxxxxxx>
Delivery-date: Mon, 20 Apr 2009 11:30:42 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <49ECB001.9060202@xxxxxxxxx>
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/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <49E61DED.7030607@xxxxxxxxxxxxxxxxxxxxx> <90eb1dc70904200828p1b781433k315849f8741c1223@xxxxxxxxxxxxxx> <49ECB001.9060202@xxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: KMail/1.11.2 (Linux/2.6.27-14-generic; KDE/4.2.2; x86_64; ; )
Jan Kalcic wrote:> Now I think I can figure out that there is no difference 
between a domU
> based on a file block device on top of a cluster file system, let's
> suppose OCFS2, and a domU based on physical block device on top of LVM
> (cLVM). In both case, I am eventually able to run the domU on both nodes
> having data corruption. Neither OCFS2 nor cLVM with their different lock
> managers can provide that mechanism to assure consistency. Right? If
> yes, I would say that the best solution should always be using LVM, at
> least it provides more features.

right.  they manage very different things (cLVM gives you blockdevices, while 
OCFS gives you files); but Xen can use either one for the same purpose (storage 
for DomUs), and neither of them will prevent several nodes clashing each other 
when using the same 'thing' (file or blockdevice) at the same time.  just like 
a non-cluster filesystem can't prevent two different processes from corrupting 
a datafile by writing at the same time.

for that there are some scripts for HA (hearbeat2) that manage Xen instances as 
'cluster resources', and make sure that each one is running on exactly one node.


Xen-users mailing list