[Linux-cluster] vm.sh with and without virsh

[brem belguebli]

Hi,

To give an example of setup that did "surprisingly" work like a charm
out of the box  (RHEL 5.4 KVM)

-  3 nodes cluster (RHEL 5.4 x86_64)
-  2  50 GB SAN LUN's (partitionned p1= 100 MB, p2=49.9 GB)
    /dev/mpath/mpath4 (mpath4p1, mpath4p2)
    /dev/mpath/mpath5 (mpath5p1, mpath5p2)
-  3 mirrored LV's  lvolVM1, lvolVM2 and lvolVM3 on mpath4p2/mpath5p2
and mpath4p1 as mirrorlog
- cmirror to maintain mirror log across the cluster
LV's are activated "shared", ie active on all nodes,  no exclusive
activation being used.

Each VM using a LV as virtual disk device (VM XML conf file):

 <disk type='block' device='disk'>
      <source dev='/dev/VMVG/lvolVM1'/> <-- for VM1

Each VM being defined in the cluster.conf with no hierarchical
dependency on anything:

<rm>
               <vm autostart="0" name="testVM1" recovery="restart"
use_virsh="1"/>
               <vm autostart="0" name="testVM2" recovery="restart"
use_virsh="1"/>
               <vm autostart="0" name="testVM3" recovery="restart"
use_virsh="1"/>
</rm>

Failover and live migration work fine
VM's must be defined on all nodes (after creation on one node, copy
the VM xml conf file to the other nodes and issue a virsh define
/Path/to/the/xml file)

The only thing that may look unsecure is the fact that the LV's are
active on all the nodes, a problem could happen if someone manually
started the VM's on some nodes while already active on another one.

I'll try the setup with exclusive activation and check if live
migration still works (I doubt that).

Brem







2009/10/5, Lon Hohberger <lhh at redhat.com>:
> On Mon, 2009-10-05 at 09:10 -0300, Edson Marquezani Filho wrote:
> > >
> > > What distribution are you using, and what is the version of rgmanager &
> > > cman?
> > >
> > > I'm interested in testing virsh too, because I also noticed those
> > > problems with xm (stalling while migrating). I'm on RHEL 5.3.
> > >
> >
> > I would like to hear from those who have some experience with vm.sh:
> > can it be used as a resource on a service configuration for Rgmanager?
> > I say this because all examples I have seen use it as a separated
> > statement on cluster.conf, not within a service declaration. But, in
> > order to put VMs up, I need to satisfy some requisites first, like LVs
> > activations on the node.
>
> You can use <vm> as a child of <service>, but you can't migrate them if
> you do.
>
> -- Lon
>
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