[ClusterLabs] large cluster - failure recovery

Wed Nov 4 20:32:10 UTC 2015

On 11/04/2015 12:55 PM, Digimer wrote:
> On 04/11/15 01:50 PM, Radoslaw Garbacz wrote:
>> Hi,
>>
>> I have a cluster of 32 nodes, and after some tuning was able to have it
>> started and running,
> 
> This is not supported by RH for a reasons; it's hard to get the timing
> right. SUSE supports up to 32 nodes, but they must be doing some serious
> magic behind the scenes.
> 
> I would *strongly* recommend dividing this up into a few smaller
> clusters... 8 nodes per cluster would be max I'd feel comfortable with.
> You need your cluster to solve more problems than it causes...

Hi Radoslaw,

RH supports up to 16. 32 should be possible with recent
pacemaker+corosync versions and careful tuning, but it's definitely
leading-edge.

An alternative with pacemaker 1.1.10+ (1.1.12+ recommended) is Pacemaker
Remote, which easily scales to dozens of nodes:
http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Remote/index.html

Pacemaker Remote is a really good approach once you start pushing the
limits of cluster nodes. Probably better than trying to get corosync to
handle more nodes. (There are long-term plans for improving corosync's
scalability, but that doesn't help you now.)

>> but it does not recover from a node disconnect-connect failure.
>> It regains quorum, but CIB does not recover to a synchronized state and
>> "cibadmin -Q" times out.
>>
>> Is there anything with corosync or pacemaker parameters I can do to make
>> it recover from such a situation
>> (everything works for smaller clusters).
>>
>> In my case it is OK for a node to disconnect (all the major resources
>> are shutdown)
>> and later reconnect the cluster (the running monitoring agent will
>> cleanup and restart major resources if needed),
>> so I do not have STONITH configured.
>>
>> Details:
>> OS: CentOS 6
>> Pacemaker: Pacemaker 1.1.9-1512.el6
> 
> Upgrade.

If you can upgrade to the latest CentOS 6.7, you can get a much newer
Pacemaker. But Pacemaker is probably not limiting your cluster nodes;
the newer version's main benefit would be Pacemaker Remote support. (Of
course there are plenty of bug fixes and new features as well.)

>> Corosync: Corosync Cluster Engine, version '2.3.2'
> 
> This is not supported on EL6 at all. Please stick with corosync 1.4 and
> use the cman pluging as the quorum provider.

CentOS is self-supported anyway, so if you're willing to handle your own
upgrades and such, nothing wrong with compiling. But corosync is up to
2.3.5 so you're already behind. :) I'd recommend compiling libqb 0.17.2
if you're compiling recent corosync and/or pacemaker.

Alternatively, CentOS 7 will have recent versions of everything.

>> Corosync configuration:
>>         token: 10000
>>         #token_retransmits_before_loss_const: 10
>>         consensus: 15000
>>         join: 1000
>>         send_join: 80
>>         merge: 1000
>>         downcheck: 2000
>>         #rrp_problem_count_timeout: 5000
>>         max_network_delay: 150 # for azure
>>
>>
>> Some logs:
>>
>> [...]
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> cib_process_diff:         Diff 1.9254.1 -> 1.9255.1 from local not
>> applied to 1.9275.1: current "epoch" is greater than required
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> update_cib_cache_cb:      [cib_diff_notify] Patch aborted: Application
>> of an update diff failed (-1006)
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> cib_process_diff:         Diff 1.9255.1 -> 1.9256.1 from local not
>> applied to 1.9275.1: current "epoch" is greater than required
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> update_cib_cache_cb:      [cib_diff_notify] Patch aborted: Application
>> of an update diff failed (-1006)
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> cib_process_diff:         Diff 1.9256.1 -> 1.9257.1 from local not
>> applied to 1.9275.1: current "epoch" is greater than required
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> update_cib_cache_cb:      [cib_diff_notify] Patch aborted: Application
>> of an update diff failed (-1006)
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> cib_process_diff:         Diff 1.9257.1 -> 1.9258.1 from local not
>> applied to 1.9275.1: current "epoch" is greater than required
>> Nov 04 17:50:18 [7985] ip-10-142-181-98 stonith-ng:   notice:
>> update_cib_cache_cb:      [cib_diff_notify] Patch aborted: Application
>> of an update diff failed (-1006)
>> [...]
>>
>> [...]
>> Nov 04 17:43:24 [12176] ip-10-109-145-175    crm_mon:    error:
>> cib_native_perform_op_delegate:         Couldn't perform cib_query
>> operation (timeout=120s): Operation already in progress (-114)
>> Nov 04 17:43:24 [12176] ip-10-109-145-175    crm_mon:    error:
>> get_cib_copy:   Couldnt retrieve the CIB
>> Nov 04 17:43:24 [12176] ip-10-109-145-175    crm_mon:    error:
>> cib_native_perform_op_delegate:         Couldn't perform cib_query
>> operation (timeout=120s): Operation already in progress (-114)
>> Nov 04 17:43:24 [12176] ip-10-109-145-175    crm_mon:    error:
>> get_cib_copy:   Couldnt retrieve the CIB
>> Nov 04 17:47:40 [10599] ip-10-109-145-175 corosync notice  [QUORUM]
>> Members[32]: 3 27 11 29 23 21 24 9 17 12 32 13 2 10 16 15 6 28 19 1 22 26 5\
>> Nov 04 17:47:40 [10599] ip-10-109-145-175 corosync notice  [QUORUM]
>> Members[32]: 14 20 31 30 8 25 18 7 4
>> Nov 04 17:47:40 [10599] ip-10-109-145-175 corosync notice  [MAIN  ]
>> Completed service synchronization, ready to provide service.
>> Nov 04 18:06:55 [10599] ip-10-109-145-175 corosync notice  [QUORUM]
>> Members[32]: 3 27 11 29 23 21 24 9 17 12 32 13 2 10 16 15 6 28 19 1 22 26 5\
>> Nov 04 18:06:55 [10599] ip-10-109-145-175 corosync notice  [QUORUM]
>> Members[32]: 14 20 31 30 8 25 18 7 4
>> [...]
>>
>> [...]
>> Nov 04 18:21:15 [17749] ip-10-178-149-131 stonith-ng:   notice:
>> update_cib_cache_cb:    [cib_diff_notify] Patch aborted: Application of
>> an update diff failed (-1006)
>> Nov 04 18:21:15 [17749] ip-10-178-149-131 stonith-ng:     info:
>> apply_xml_diff:         Digest mis-match: expected
>> 01192e5118739b7c33c23f7645da3f45, calculated
>> f8028c0c98526179ea5df0a2ba0d09de
>> Nov 04 18:21:15 [17749] ip-10-178-149-131 stonith-ng:  warning:
>> cib_process_diff:       Diff 1.15046.2 -> 1.15046.3 from local not
>> applied to 1.15046.2: Failed application of an update diff
>> Nov 04 18:21:15 [17749] ip-10-178-149-131 stonith-ng:   notice:
>> update_cib_cache_cb:    [cib_diff_notify] Patch aborted: Application of
>> an update diff failed (-1006)
>> Nov 04 18:21:15 [17749] ip-10-178-149-131 stonith-ng:   notice:
>> cib_process_diff:       Diff 1.15046.2 -> 1.15046.3 from local not
>> applied to 1.15046.3: current "num_updates" is greater than required
>> [...]
>>
>>
>> ps. Sorry if should posted on corosync newsgroup, just the CIB
>> synchronization fails, so this group seemed to me the right place.
> 
> All of the HA mailing lists are merging into Cluster labs. This is the
> right place to ask.
> 
>> -- 
>> Best Regards,
>>
>> Radoslaw Garbacz
> 