From the log, we can see that the lvextend command took 18 sec, which is quite long.

60decf0c-6d9a-4c3b-bee6-de9d2ff05e85::DEBUG::2016-04-13 10:52:06,759::lvm::290::Storage.Misc.excCmd::(cmd) /usr/bin/taskset --cpu-list 0-23 /usr/bin/sudo -n /usr/sbin/lvm lvextend --config ' devices { preferred_names = ["^/dev/mapper/"] ignore_suspended_devices=1 write_cache_state=0 disable_after_error_count=3 filter = [ '\''a|/dev/mapper/36000eb3a4f1acbc20000000000000043|'\'', '\''r|.*|'\'' ] }  global {  locking_type=1  prioritise_write_locks=1  wait_for_locks=1  use_lvmetad=0 }  backup {  retain_min = 50  retain_days = 0 } ' --autobackup n --size 6016m 5de4a000-a9c4-489c-8eee-10368647c413/721d09bc-60e7-4310-9ba2-522d2a4b03d0 (cwd None)
....
60decf0c-6d9a-4c3b-bee6-de9d2ff05e85::DEBUG::2016-04-13 10:52:22,217::lvm::290::Storage.Misc.excCmd::(cmd) SUCCESS: <err> = '  WARNING: lvmetad is running but disabled. Restart lvmetad before enabling it!\n  WARNING: This metadata update is NOT backed up\n'; <rc> = 0


The watermark can be configured by the following value:

'volume_utilization_percent', '50',
    'Together with volume_utilization_chunk_mb, set the minimal free '
    'space before a thin provisioned block volume is extended. Use '
    'lower values to extend earlier.')

On Thu, Apr 14, 2016 at 11:42 AM, Michal Skrivanek <michal.skrivanek@redhat.com> wrote:

> On 14 Apr 2016, at 09:57, nicolas@devels.es wrote:
>
> Ok, that makes sense, thanks for the insight both Alex and Fred. I'm attaching the VDSM log of the SPM node at the time of the pause. I couldn't find anything that would clearly identify the problem, but maybe you'll be able to.

In extreme conditions it will happen. When your storage is slow to respond to extension request, and when your write rate is very high then it may happen, as it is happening to you, that you run out space sooner than the extension finishes. You can change the watermark value I guess(right, Fred?), but better would be to plan a bit more ahead and either use preallocated or create thin and then allocate expected size in advance before the operation causing it (typically it only happens during untarring gigabytes of data, or huge database dump/restore)
Even then, the VM should always be automatially resumed once the disk space is allocated

Thanks,
michal

>
> Thanks.
>
> Regards.
>
> El 2016-04-13 13:09, Fred Rolland escribió:
>> Hi,
>> Yes, just as Alex explained, if the disk has been created as thin
>> provisioning, the vdsm will extends once a watermark is reached.
>> Usually it should not get to the state the Vm is paused.
>> From the log, you can see that the request for extension has been sent
>> before the VM got to the No Space Error.
>> Later, we can see the VM resuming.
>> INFO::2016-04-13
>> 10:52:04,182::vm::1026::virt.vm::(extendDrivesIfNeeded)
>> vmId=`f9cd282e-110a-4896-98d3-6d320662744d`::Requesting extension for
>> volume
>> ....
>> INFO::2016-04-13 10:52:29,360::vm::3728::virt.vm::(onIOError)
>> vmId=`f9cd282e-110a-4896-98d3-6d320662744d`::abnormal vm stop device
>> virtio-disk0 error enospc
>> ....
>> INFO::2016-04-13 10:52:54,317::vm::5084::virt.vm::(_logGuestCpuStatus)
>> vmId=`f9cd282e-110a-4896-98d3-6d320662744d`::CPU running: onResume
>> Note that the extension is done on the SPM host, so it would be
>> interesting to see the vdsm log from the host that was in SPM role at
>> this timeframe.
>> Regards,
>> Fred
>> On Wed, Apr 13, 2016 at 2:43 PM, Alex Crow <acrow@integrafin.co.uk>
>> wrote:
>>> Hi,
>>> If you have set up VM disks as Thin Provisioned, the VM has to
>>> pause when the disk image needs to expand. You won't see this on VMs
>>> with preallocated storage.
>>> It's not the SAN that's running out of space, it's the VM image
>>> needing to be expanded incrementally each time.
>>> Cheers
>>> Alex
>>> On 13/04/16 12:04, nicolas@devels.es wrote:
>>> Hi Fred,
>>> This is an iSCSI storage. I'm attaching the VDSM logs from the host
>>> where this machine has been running. Should you need any further
>>> info, don't hesitate to ask.
>>> Thanks.
>>> Regards.
>>> El 2016-04-13 11:54, Fred Rolland escribió:
>>> Hi,
>>> What kind of storage do you have ? (ISCSI,FC,NFS...)
>>> Can you provide the vdsm logs from the host where this VM runs ?
>>> Thanks,
>>> Freddy
>>> On Wed, Apr 13, 2016 at 1:02 PM, <nicolas@devels.es> wrote:
>>> Hi,
>>> We're running oVirt 3.6.4.1-1. Lately we're seeing a bunch of
>>> events like these:
>>> 2016-04-13 10:52:30,735 INFO
>>> [org.ovirt.engine.core.vdsbroker.VmAnalyzer]
>>> (DefaultQuartzScheduler_Worker-86) [60dea18f] VM
>>> 'f9cd282e-110a-4896-98d3-6d320662744d'(vm.domain.com [1] [1]) moved
>>> from
>>> 'Up' --> 'Paused'
>>> 2016-04-13 10:52:30,815 INFO
>> [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector]
>>> (DefaultQuartzScheduler_Worker-86) [60dea18f] Correlation ID: null,
>>> Call Stack: null, Custom Event ID: -1, Message: VM vm.domain.com
>>> [1] [1]
>>> has been paused.
>>> 2016-04-13 10:52:30,898 ERROR
>> [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector]
>>> (DefaultQuartzScheduler_Worker-86) [60dea18f] Correlation ID: null,
>>> Call Stack: null, Custom Event ID: -1, Message: VM vm.domain.com
>>> [1] [1]
>>> has been paused due to no Storage space error.
>>> 2016-04-13 10:52:52,320 WARN
>>> [org.ovirt.engine.core.vdsbroker.irsbroker.IrsProxyData]
>>> (org.ovirt.thread.pool-8-thread-38) [] domain
>>> '5de4a000-a9c4-489c-8eee-10368647c413:iscsi01' in problem. vds:
>>> 'host6.domain.com [2] [2]'
>>> 2016-04-13 10:52:55,183 INFO
>>> [org.ovirt.engine.core.vdsbroker.VmAnalyzer]
>>> (DefaultQuartzScheduler_Worker-70) [3da0f3d4] VM
>>> 'f9cd282e-110a-4896-98d3-6d320662744d'(vm.domain.com [1] [1]) moved
>>> from
>>> 'Paused' --> 'Up'
>>> 2016-04-13 10:52:55,318 INFO
>> [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector]
>>> (DefaultQuartzScheduler_Worker-70) [3da0f3d4] Correlation ID: null,
>>> Call Stack: null, Custom Event ID: -1, Message: VM vm.domain.com
>>> [1] [1]
>>> has recovered from paused back to up.
>>> The storage domain is far from being full, though (400+ G available
>>> right now). Could this be related to this other issue [1]? If not,
>>> how could I debug what's going on?
>>> Thanks.
>>>  [1]: https://www.mail-archive.com/users@ovirt.org/msg32079.html
>>> [3]
>>> [3]
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>>> [2] http://host6.domain.com [2]
>>> [3] https://www.mail-archive.com/users@ovirt.org/msg32079.html [3]
>>> [4] http://lists.ovirt.org/mailman/listinfo/users [4]
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