[Linux-cluster] ZEN with GFS

[Bernard Chew]

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com [mailto:linux-cluster-
> bounces at redhat.com] On Behalf Of Lon Hohberger
> Sent: Tuesday, March 11, 2008 6:00 AM
> To: isplist at logicore.net; linux clustering
> Subject: Re: [Linux-cluster] ZEN with GFS
> 
> On Mon, Mar 10, 2008 at 01:53:40PM -0600, isplist at logicore.net wrote:
> > A while back, someone posted about their setting up ZEN with GFS as
> the
> > central storage.
> >
> > Was that central storage for your virtual machines or because you
> needed a
> > shared data area for the VM's?
> 
> You can do either -- that is, you can mount GFS on domain-0 nodes
> (physical nodes) and use GFS to host file system images for the guest
> machines.
> 
> Alternatively, you could also provide GFS to domain-Us
> (unprivileged/guest Xen domains).  Rob Kenna wrote a Red Hat Magazine
> article about how to do the former, and I've done the latter.
> 
> I'm not sure how many people have tried both simultaneously - that is,
> I
> don't know if GFS on the dom0 machines has been used to host a GFS
> image
> on the domU machines; when I did shared-images between domUs, it was
on
> ext3 on a single machine (dom0s were not clustered).
> 
> Maybe others could comment about their experiences.
> 
> -- lon
> 
> 
> --
> Lon Hohberger - Software Engineer - Red Hat, Inc.
> 
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster

Hi,

Just to share, 

In my production environment, I've 5 physical hosts connecting to a
central shared storage (MD3000i) using iscsi. 2 virtual disks were
created in the MD3000i; a 200GB virtual disk for 10 xen guest images
(Apache, MySQL, Tomcat, etc), and a 1TB virtual disk for data storage.
Both virtual disks are formatted with GFS. The first virtual disk is
mounted in the dom0 cluster (containing all the physical hosts) and 2
xen guests are started in each host from the shared storage. The 1TB
virtual disk is then mounted after the domU cluster (containing all the
virtual guests) is up.

The multipath works nicely for the 1TB data virtual disk, and the
virtual guests have no problems accessing the data storage in the event
of failover. The same cannot be say for the 200GB virtual disk that
contains the xen guest images because the virtual guests will freeze in
the event of failover.

I'm still trying to access if I need the automated failover of
virtualized guests feature. If not, I'll probably keep 2 virtual guests
on each physical host instead.

Regards,
Bernard Chew