[ClusterLabs] ocf:lvm2:VolumeGroup Probe Issue

[Marc Smith]

Perfect, thanks for the quick reply.

--Marc

On Tue, Nov 8, 2016 at 12:00 PM, Ken Gaillot <kgaillot at redhat.com> wrote:
> On 11/08/2016 10:37 AM, Marc Smith wrote:
>> Hi,
>>
>> First, I realize ocf:lvm2:VolumeGroup comes from the LVM2 package and
>> not resource-agents, but I'm hoping someone on this list is familiar
>> with this RA and can provide some insight.
>>
>> In my cluster configuration, I'm using ocf:lvm2:VolumeGroup to manage
>> my LVM VG's, and I'm using the cluster to manage DLM and CLVM. I have
>> my constraints in place and everything seems to be working mostly,
>> except I'm hitting a glitch with ocf:lvm2:VolumeGroup and the initial
>> probe operation.
>>
>> On startup, a probe operation (monitor) is issued for all of the
>> resources, but ocf:lvm2:VolumeGroup is returning OCF_ERR_GENERIC in
>> VolumeGroup_status() (via VolumeGroup_monitor()) since clvmd hasn't
>> started yet... this line in VolumeGroup_status() is the trouble:
>>
>> VGOUT=`vgdisplay -v $OCF_RESKEY_volgrpname 2>&1` || exit $OCF_ERR_GENERIC
>>
>> When clvmd is not running, 'vgdisplay -v name' will always return
>> something like this:
>>
>> --snip--
>>   connect() failed on local socket: No such file or directory
>>   Internal cluster locking initialisation failed.
>>   WARNING: Falling back to local file-based locking.
>>   Volume Groups with the clustered attribute will be inaccessible.
>>     VG name on command line not found in list of VGs: biggie
>>   Volume group "biggie" not found
>>   Cannot process volume group biggie
>> --snip--
>>
>> And exits with a status of 5. So, my question is, do I patch the RA?
>> Or is there some cluster constraint I can add so a probe/monitor
>> operation isn't performed for the VolumeGroup resource until CLVM has
>> been started?
>
> Ordered probes is a desired feature for Pacemaker, but the
> implementation is much trickier than it appears at first glance, so
> there's no timeline for when it might arrive.
>
> In the meantime, patching the RA to exit with "not running" in this
> situation is probably the best workaround. There is a library function
> ocf_is_probe you can use to avoid messing with "real" monitors.
>
>> Any other advice? Is ocf:heartbeat:LVM or ocf:lvm2:VolumeGroup the
>> more popular RA for managing LVM VG's? Any comments from other users
>> on experiences using either (good, bad)? Both appear to achieve the
>> same function, just a bit differently.
>>
>>
>> Thanks,
>>
>> Marc
>
> _______________________________________________
> Users mailing list: Users at clusterlabs.org
> http://clusterlabs.org/mailman/listinfo/users
>
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> Bugs: http://bugs.clusterlabs.org