WARNING - OLD ARCHIVES

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/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-users

Re: [Xen-users] Re: cLVM on Debian/Lenny

To: Javier Guerra <javier@xxxxxxxxxxx>
Subject: Re: [Xen-users] Re: cLVM on Debian/Lenny
From: Jan Kalcic <jandot@xxxxxxxxxxxxxx>
Date: Mon, 20 Apr 2009 22:08:08 +0200
Cc: Jan Kalcic <jandot@xxxxxxxxxxxxxx>, Olivier Le Cam <Olivier.LeCam@xxxxxxxxxxxxxxxxxxxxx>, John Madden <jmadden@xxxxxxxxxxx>, Ferenc Wagner <wferi@xxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx, Thiago Camargo Martins Cordeiro <thiagocmartinsc@xxxxxxxxx>
Delivery-date: Mon, 20 Apr 2009 13:08:20 -0700
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from :user-agent:mime-version:to:cc:subject:references:in-reply-to :content-type:content-transfer-encoding; bh=9CsaUT5nrcwL9wyTvRome1A339DLkatDdNye/gVQaIs=; b=LEEj+3fJunKv9TXudMUdmYTfQwGlCtR0M8VuUNIbHMqHDPvj+aZ7kn2WG1WgQXazK/ G9mUzzCxRJXyeL4Gz2qgpLY7Q505sWIL7RDz9F/W/1RmSdkcwKd+ki0DKglz//VoGrAw 89vJifG7W4rGxBbKVGNHw53dsqDNtjJB0E7bw=
Domainkey-signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=PjmcFNkUreXe5VrGKO0l2KyO+skCwrstm15vsjSfGoDrDqHELl7PBfsPM5YN8mOgQ0 s7uou8zlT67zLE4v9B/zd+yhhinCBSyzU5XfADAY64aJEqz2PwdWt6oLrleg2J+BpvSb 9MOQHoYA4gvDKy96Q2nD+O9wsVxCKS3FXJkBY=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <200904201329.56282.javier@xxxxxxxxxxx>
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> <200904201329.56282.javier@xxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird 2.0.0.19 (X11/20081227)
Javier Guerra wrote:
>
>
> 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.
>
>  
>   
That's very clear and you got it, HA. With Xen in HA, like any other
kind of resource, you can obviously start manually a domU from console
or virt-manager and so you are not sure it is running on one node only.
Of course, you don't manage clustered resources (usually services or
whatever) without hearbeat, otherwise you end up to face strange and
unpredictable behavior. What would be really useful here, is a kind of
lock which prevent a domU already running on a dom0 to be started on
another domU.I wrongly expected this was managed by cLVM and now which
everything is explained I see the reason why it cannot be done and I
look forward to see such a kind of mechanism implemented in Xen.

Thanks,
Jan

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users