[one-users] What is the best way to reboot a storage server in order to cause the least amount of disruption to running VMs?

[Shankhadeep Shome]

I think suspend resume would work fine, I would do the following..

1. Disable network connectivity to the system thought some firewall rule so
you don't have active users on the system.
2. Pause all the VMs, this should keep your VMs safe.
3. Safely shut down your open nebula controller and database
4. Reconfigure your NFS server and restart it. You may also want to
dismount the nfs mounts on your hypervisors
5. Start up the vms in such a way that the virtual infrastructure comes up
before your application vms. Start iSCSI target vms before your initiators
try to connect to them, etc

I would take a close look at HA nfs services, glusterfs is another option
you might like to try. You don't need anything special for glusterfs.fuse
support in open nebula.




On Tue, Apr 29, 2014 at 2:53 PM, Michael <michael at onlinefusion.co.uk> wrote:

> Hi Gerry,
>
> While I don't have any recommendations on the reboot process, if you're
> using KVM I'd certainly recommend Ceph as a solution for high availability
> storage. We've gone as far as rolling linux distribution upgrades to our
> storage cluster with no loss of VM connectivity.
>
> -Michael
>
>
> On 29/04/2014 16:50, Gerry O'Brien wrote:
>
>> Hi,
>>
>>     Our OpenNebula Debian Wheezy storage server has been running for 466
>> days and needs to be rebooted as there have been many kernel patches during
>> this time. It exports the datastores to the hosts using NFS.
>>
>>     What is the best way to reboot the server in order to cause the least
>> amount of disruption to running VMs? I've thought about suspending all
>> running VMs, rebooting the storage server and resuming the VMs after the
>> storages serveris back. Would this work? Obviously, any VMs that have to
>> maintain real time connections would be in trouble, e.g. iSCSI mounts, but
>> would an ordinary machines resume successfully after the storage server
>> reboots. The host NFS mounts are as here: /datastores
>> nfs vers=4,bg,rw,_netdev,fsc,rsize=32768,wsize=32768,intr,noatime
>>
>>     In general, is there a recommended way of providing HA storage to
>> hosts?
>>
>>             Regards,
>>                 Gerry
>>
>>
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