[Openstack-operators] Cinde block storage HA

Juan José Pavlik Salles jjpavlik at gmail.com
Tue Sep 16 19:42:34 UTC 2014

Now I get it, thanks. Neither the EMC nor the HP storages export through
NFS, at least not the versions we've got. So NFS it's not a possible option

2014-09-16 16:27 GMT-03:00 Abel Lopez <alopgeek at gmail.com>:

> Yes, you can export your large luns from the EMC via NFS to both your
> cinder-volume servers. That way they both have access to everything. Of
> course, you’d need to ensure that cinder user has the same UID on both
> nodes, and both nodes need root permissions on the shares.
> Check out the docs
> http://docs.openstack.org/admin-guide-cloud/content/nfs_backend.html
> On Sep 16, 2014, at 12:23 PM, Juan José Pavlik Salles <jjpavlik at gmail.com>
> wrote:
> I'm not sure to be getting your idea here, how would you do it with NFS?
> Who would be the NFS exporting server?
> As you can see I don't have too much experience with cinder at all, we've
> been using the LVM driver since we installed it a year and a half ago.
> 2014-09-16 16:09 GMT-03:00 Abel Lopez <alopgeek at gmail.com>:
>> Some of your concerns might be addressed by switching to NFS as the
>> protocol.
>> You’re already exporting large luns to your cinder-volume servers, using
>> NFS they would both be writeable by both nodes, so if one goes down, there
>> is no need to “swing luns over”
>> On Sep 16, 2014, at 11:27 AM, Juan José Pavlik Salles <jjpavlik at gmail.com>
>> wrote:
>> Hi Abel, I thought about trying it, but We had MANY performance problems
>> with the EMC because of running too many LUNs that's way we`d like to avoid
>> that scenario. It might seem the best solution but We don't want to go that
>> way again.
>> 2014-09-16 15:20 GMT-03:00 Abel Lopez <alopgeek at gmail.com>:
>>> Have you tried using the native Emc drivers? That way cinder only acts
>>> as a broker between your instances and the storage back end, and you don't
>>> need to worry about your cinder-volume service being HA. (As much)
>>> On Tuesday, September 16, 2014, Juan José Pavlik Salles <
>>> jjpavlik at gmail.com> wrote:
>>>> Hi guys, I'm trying to put some HA on our cinder service, we have the
>>>> next scenario:
>>>> -Real backends: EMC clarion (SATA drives) and HP Storevirtual P4000
>>>> (SAS drives), this two backends export 2 big LUNs to our (one and only
>>>> right now) cinder server.
>>>> -Once these big LUNs are imported in the cinder server, two different
>>>> VG are created for two different cinder LVM drivers (cinder-volumes-1 and
>>>> cinder-volumes-2). This way I have two different storage resources to give
>>>> to my tenants.
>>>> What I want is to deploy a second cinder server to act as failover of
>>>> the first one. Both servers are identical. So far I'm running a few tests
>>>> with isolated VMs.
>>>> -I installed corosync+pacemaker in 2 VMs, added a Virtual IP.
>>>> -Imported in the VMs a LUN with iSCSI created a VG
>>>> -Exported a LV with tgt. More or less the same scenario we have on
>>>> production.
>>>> If one of the VMs die the second one picks the virtual IP throughtout
>>>> tgt is exporting the LUN and the iSCSI session doesn't die, here you can
>>>> see part of the logs where the LUN is being imported:
>>>> Sep 16 14:29:50 borrar-nfs kernel: [86630.416160]  connection1:0: ping
>>>> timeout of 5 secs expired, recv timeout 5, last rx 4316547395, last ping
>>>> 4316548646, now 4316549900
>>>> Sep 16 14:29:50 borrar-nfs kernel: [86630.418938]  connection1:0:
>>>> detected conn error (1011)
>>>> Sep 16 14:29:51 borrar-nfs iscsid: Kernel reported iSCSI connection 1:0
>>>> error (1011) state (3)
>>>> Sep 16 14:29:53 borrar-nfs iscsid: connection1:0 is operational after
>>>> recovery (1 attempts)
>>>> This test was really simple, just one 1GB LUN but it worked ok, even
>>>> when the failover was tested during a writing operation.
>>>> So it seems to be a good-so-far-solution, but there are a few things
>>>> that worries me a bit:
>>>> -Timeouts? How much time do I have to detect the problem and move the
>>>> IP to the new node before the iscsi connections die. I think I could play a
>>>> little bit with timeo.noop_out_timeout in iscsid.conf
>>>> -What if there was a write operation going on while a node failed, what
>>>> if this operation never reached the real backends, could I come across some
>>>> inconsistencies in the volume FS? Any recommendations?
>>>> -If I create a volume in cinder, the proper target file is created
>>>> in /var/lib/cinder/volumes/volue-* but, I need the file to be created in
>>>> both cinder nodes in case one of them fail. What would be a proper solution
>>>> for this? shared storage for the directory? SVN?
>>>> -Both servers should be running tgt at the same time or maybe I should
>>>> start tgt on the failover server once the virtual IP is changed?
>>>> Any comments or suggestions will be more than appreciated. Thanks!
>>>> --
>>>> Pavlik Salles Juan José
>>>> Blog - http://viviendolared.blogspot.com
>> --
>> Pavlik Salles Juan José
>> Blog - http://viviendolared.blogspot.com
> --
> Pavlik Salles Juan José
> Blog - http://viviendolared.blogspot.com

Pavlik Salles Juan José
Blog - http://viviendolared.blogspot.com
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