[ClusterLabs] Antw: Re: Antw: Unexpected Resource movement after failover

Ken Gaillot kgaillot at redhat.com
Mon Oct 17 18:06:28 UTC 2016


On 10/17/2016 09:55 AM, Nikhil Utane wrote:
> I see these prints. 
> 
> pengine:     info: rsc_merge_weights:cu_4: Rolling back scores from cu_3 
> pengine:    debug: native_assign_node:Assigning Redun_CU4_Wb30 to cu_4    
> pengine:     info: rsc_merge_weights:cu_3: Rolling back scores from cu_2 
> pengine:    debug: native_assign_node:Assigning Redund_CU5_WB30 to cu_3   
> 
> Looks like rolling back the scores is causing the new decision to
> relocate the resources.
> Am I using the scores incorrectly?

No, I think this is expected.

Your anti-colocation constraints place cu_2 and cu_3 relative to cu_4,
so that means the cluster will place cu_4 first if possible, before
deciding where the others should go. Similarly, cu_2 has a constraint
relative to cu_3, so cu_3 gets placed next, and cu_2 is the one left out.

The anti-colocation scores of -INFINITY outweigh the stickiness of 100.
I'm not sure whether setting stickiness to INFINITY would change
anything; hopefully, it would stop cu_3 from moving, but cu_2 would
still be stopped.

I don't see a good way around this. The cluster has to place some
resource first, in order to know not to place some other resource on the
same node. I don't think there's a way to make them "equal", because
then none of them could be placed to begin with -- unless you went with
utilization attributes, as someone else suggested, with
placement-strategy=balanced:

http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#idm140521708557280

> 
> [root at Redund_CU5_WB30 root]# pcs constraint
> Location Constraints:
>   Resource: cu_2
>     Enabled on: Redun_CU4_Wb30 (score:0)
>     Enabled on: Redund_CU5_WB30 (score:0)
>     Enabled on: Redund_CU3_WB30 (score:0)
>     Enabled on: Redund_CU1_WB30 (score:0)
>   Resource: cu_3
>     Enabled on: Redun_CU4_Wb30 (score:0)
>     Enabled on: Redund_CU5_WB30 (score:0)
>     Enabled on: Redund_CU3_WB30 (score:0)
>     Enabled on: Redund_CU1_WB30 (score:0)
>   Resource: cu_4
>     Enabled on: Redun_CU4_Wb30 (score:0)
>     Enabled on: Redund_CU5_WB30 (score:0)
>     Enabled on: Redund_CU3_WB30 (score:0)
>     Enabled on: Redund_CU1_WB30 (score:0)
> Ordering Constraints:
> Colocation Constraints:
>   cu_2 with cu_4 (score:-INFINITY)
>   cu_3 with cu_4 (score:-INFINITY)
>   cu_2 with cu_3 (score:-INFINITY)
> 
> 
> On Mon, Oct 17, 2016 at 8:16 PM, Nikhil Utane
> <nikhil.subscribed at gmail.com <mailto:nikhil.subscribed at gmail.com>> wrote:
> 
>     This is driving me insane. 
> 
>     This is how the resources were started. Redund_CU1_WB30  was the DC
>     which I rebooted.
>      cu_4(ocf::redundancy:RedundancyRA):Started Redund_CU1_WB30 
>      cu_2(ocf::redundancy:RedundancyRA):Started Redund_CU5_WB30 
>      cu_3(ocf::redundancy:RedundancyRA):Started Redun_CU4_Wb30 
> 
>     Since the standby node was not UP. I was expecting resource cu_4 to
>     be waiting to be scheduled.
>     But then it re-arranged everything as below.
>      cu_4(ocf::redundancy:RedundancyRA):Started Redun_CU4_Wb30 
>      cu_2(ocf::redundancy:RedundancyRA):Stopped 
>      cu_3(ocf::redundancy:RedundancyRA):Started Redund_CU5_WB30 
> 
>     There is not much information available in the logs on new DC. It
>     just shows what it has decided to do but nothing to suggest why it
>     did it that way.
> 
>     notice: Start   cu_4(Redun_CU4_Wb30)                           
>     notice: Stop    cu_2(Redund_CU5_WB30)                          
>     notice: Move    cu_3(Started Redun_CU4_Wb30 -> Redund_CU5_WB30)
> 
>     I have default stickiness set to 100 which is higher than any score
>     that I have configured.
>     I have migration_threshold set to 1. Should I bump that up instead?
> 
>     -Thanks
>     Nikhil
> 
>     On Sat, Oct 15, 2016 at 12:36 AM, Ken Gaillot <kgaillot at redhat.com
>     <mailto:kgaillot at redhat.com>> wrote:
> 
>         On 10/14/2016 06:56 AM, Nikhil Utane wrote:
>         > Hi,
>         >
>         > Thank you for the responses so far.
>         > I added reverse colocation as well. However seeing some other issue in
>         > resource movement that I am analyzing.
>         >
>         > Thinking further on this, why doesn't "/a not with b" does not
>         imply "b
>         > not with a"?/
>         > Coz wouldn't putting "b with a" violate "a not with b"?
>         >
>         > Can someone confirm that colocation is required to be configured both ways?
> 
>         The anti-colocation should only be defined one-way. Otherwise,
>         you get a
>         dependency loop (as seen in logs you showed elsewhere).
> 
>         The one-way constraint is enough to keep the resources apart.
>         However,
>         the question is whether the cluster might move resources around
>         unnecessarily.
> 
>         For example, "A not with B" means that the cluster will place B
>         first,
>         then place A somewhere else. So, if B's node fails, can the cluster
>         decide that A's node is now the best place for B, and move A to
>         a free
>         node, rather than simply start B on the free node?
> 
>         The cluster does take dependencies into account when placing a
>         resource,
>         so I would hope that wouldn't happen. But I'm not sure. Having some
>         stickiness might help, so that A has some preference against moving.
> 
>         > -Thanks
>         > Nikhil
>         >
>         > /
>         > /
>         >
>         > On Fri, Oct 14, 2016 at 1:09 PM, Vladislav Bogdanov
>         > <bubble at hoster-ok.com <mailto:bubble at hoster-ok.com>
>         <mailto:bubble at hoster-ok.com <mailto:bubble at hoster-ok.com>>> wrote:
>         >
>         >     On October 14, 2016 10:13:17 AM GMT+03:00, Ulrich Windl
>         >     <Ulrich.Windl at rz.uni-regensburg.de
>         <mailto:Ulrich.Windl at rz.uni-regensburg.de>
>         >     <mailto:Ulrich.Windl at rz.uni-regensburg.de
>         <mailto:Ulrich.Windl at rz.uni-regensburg.de>>> wrote:
>         >     >>>> Nikhil Utane <nikhil.subscribed at gmail.com <mailto:nikhil.subscribed at gmail.com>
>         >     <mailto:nikhil.subscribed at gmail.com
>         <mailto:nikhil.subscribed at gmail.com>>> schrieb am 13.10.2016 um
>         >     >16:43 in
>         >     >Nachricht
>         >     ><CAGNWmJUbPucnBGXroHkHSbQ0LXovwsLFPkUPg1R8gJqRFqM9Dg at mail.gmail.com
>         <mailto:CAGNWmJUbPucnBGXroHkHSbQ0LXovwsLFPkUPg1R8gJqRFqM9Dg at mail.gmail.com>
>         >   
>          <mailto:CAGNWmJUbPucnBGXroHkHSbQ0LXovwsLFPkUPg1R8gJqRFqM9Dg at mail.gmail.com
>         <mailto:CAGNWmJUbPucnBGXroHkHSbQ0LXovwsLFPkUPg1R8gJqRFqM9Dg at mail.gmail.com>>>:
>         >     >> Ulrich,
>         >     >>
>         >     >> I have 4 resources only (not 5, nodes are 5). So then I only need 6
>         >     >> constraints, right?
>         >     >>
>         >     >>      [,1]   [,2]   [,3]   [,4]   [,5]  [,6]
>         >     >> [1,] "A"  "A"  "A"    "B"   "B"    "C"
>         >     >> [2,] "B"  "C"  "D"   "C"  "D"    "D"
>         >     >
>         >     >Sorry for my confusion. As Andrei Borzenkovsaid in
>         >     ><CAA91j0W+epAHFLg9u6VX_X8LgFkf9Rp55g3nocY4oZNA9BbZ+g at mail.gmail.com
>         <mailto:CAA91j0W%2BepAHFLg9u6VX_X8LgFkf9Rp55g3nocY4oZNA9BbZ%2Bg at mail.gmail.com>
>         >   
>          <mailto:CAA91j0W%2BepAHFLg9u6VX_X8LgFkf9Rp55g3nocY4oZNA9BbZ%2Bg at mail.gmail.com
>         <mailto:CAA91j0W%252BepAHFLg9u6VX_X8LgFkf9Rp55g3nocY4oZNA9BbZ%252Bg at mail.gmail.com>>>
>         >     >you probably have to add (A, B) _and_ (B, A)! Thinking about it, I
>         >     >wonder whether an easier solution would be using "utilization": If
>         >     >every node has one token to give, and every resource needs on token, no
>         >     >two resources will run on one node. Sounds like an easier solution to
>         >     >me.
>         >     >
>         >     >Regards,
>         >     >Ulrich
>         >     >
>         >     >
>         >     >>
>         >     >> I understand that if I configure constraint of R1 with R2 score as
>         >     >> -infinity, then the same applies for R2 with R1 score as -infinity
>         >     >(don't
>         >     >> have to configure it explicitly).
>         >     >> I am not having a problem of multiple resources getting schedule on
>         >     >the
>         >     >> same node. Rather, one working resource is unnecessarily getting
>         >     >relocated.
>         >     >>
>         >     >> -Thanks
>         >     >> Nikhil
>         >     >>
>         >     >>
>         >     >> On Thu, Oct 13, 2016 at 7:45 PM, Ulrich Windl <
>         >     >> Ulrich.Windl at rz.uni-regensburg.de
>         <mailto:Ulrich.Windl at rz.uni-regensburg.de>
>         >     <mailto:Ulrich.Windl at rz.uni-regensburg.de
>         <mailto:Ulrich.Windl at rz.uni-regensburg.de>>> wrote:
>         >     >>
>         >     >>> Hi!
>         >     >>>
>         >     >>> Don't you need 10 constraints, excluding every possible pair of your
>         >     >5
>         >     >>> resources (named A-E here), like in this table (produced with R):
>         >     >>>
>         >     >>>      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
>         >     >>> [1,] "A"  "A"  "A"  "A"  "B"  "B"  "B"  "C"  "C"  "D"
>         >     >>> [2,] "B"  "C"  "D"  "E"  "C"  "D"  "E"  "D"  "E"  "E"
>         >     >>>
>         >     >>> Ulrich
>         >     >>>
>         >     >>> >>> Nikhil Utane <nikhil.subscribed at gmail.com <mailto:nikhil.subscribed at gmail.com>
>         >     <mailto:nikhil.subscribed at gmail.com
>         <mailto:nikhil.subscribed at gmail.com>>> schrieb am 13.10.2016
>         >     >um
>         >     >>> 15:59 in
>         >     >>> Nachricht
>         >     >>>
>         >     ><CAGNWmJW0CWMr3bvR3L9xZCAcJUzyczQbZEzUzpaJxi+Pn7Oj_A at mail.gmail.com
>         <mailto:CAGNWmJW0CWMr3bvR3L9xZCAcJUzyczQbZEzUzpaJxi%2BPn7Oj_A at mail.gmail.com>
>         >   
>          <mailto:CAGNWmJW0CWMr3bvR3L9xZCAcJUzyczQbZEzUzpaJxi%2BPn7Oj_A at mail.gmail.com
>         <mailto:CAGNWmJW0CWMr3bvR3L9xZCAcJUzyczQbZEzUzpaJxi%252BPn7Oj_A at mail.gmail.com>>>:
>         >     >>> > Hi,
>         >     >>> >
>         >     >>> > I have 5 nodes and 4 resources configured.
>         >     >>> > I have configured constraint such that no two
>         resources can be
>         >     >>> co-located.
>         >     >>> > I brought down a node (which happened to be DC). I
>         was expecting
>         >     >the
>         >     >>> > resource on the failed node would be migrated to the
>         5th waiting
>         >     >node
>         >     >>> (that
>         >     >>> > is not running any resource).
>         >     >>> > However what happened was the failed node resource
>         was started on
>         >     >another
>         >     >>> > active node (after stopping it's existing resource)
>         and that
>         >     >node's
>         >     >>> > resource was moved to the waiting node.
>         >     >>> >
>         >     >>> > What could I be doing wrong?
>         >     >>> >
>         >     >>> > <nvpair id="cib-bootstrap-options-have-watchdog"
>         value="true"
>         >     >>> > name="have-watchdog"/>
>         >     >>> > <nvpair id="cib-bootstrap-options-dc-version"
>         >     >value="1.1.14-5a6cdd1"
>         >     >>> > name="dc-version"/>
>         >     >>> > <nvpair
>         id="cib-bootstrap-options-cluster-infrastructure"
>         >     >>> value="corosync"
>         >     >>> > name="cluster-infrastructure"/>
>         >     >>> > <nvpair id="cib-bootstrap-options-stonith-enabled"
>         value="false"
>         >     >>> > name="stonith-enabled"/>
>         >     >>> > <nvpair id="cib-bootstrap-options-no-quorum-policy"
>         value="ignore"
>         >     >>> > name="no-quorum-policy"/>
>         >     >>> > <nvpair
>         id="cib-bootstrap-options-default-action-timeout"
>         >     >value="240"
>         >     >>> > name="default-action-timeout"/>
>         >     >>> > <nvpair id="cib-bootstrap-options-symmetric-cluster"
>         value="false"
>         >     >>> > name="symmetric-cluster"/>
>         >     >>> >
>         >     >>> > # pcs constraint
>         >     >>> > Location Constraints:
>         >     >>> >   Resource: cu_2
>         >     >>> >     Enabled on: Redun_CU4_Wb30 (score:0)
>         >     >>> >     Enabled on: Redund_CU2_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU3_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU5_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU1_WB30 (score:0)
>         >     >>> >   Resource: cu_3
>         >     >>> >     Enabled on: Redun_CU4_Wb30 (score:0)
>         >     >>> >     Enabled on: Redund_CU2_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU3_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU5_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU1_WB30 (score:0)
>         >     >>> >   Resource: cu_4
>         >     >>> >     Enabled on: Redun_CU4_Wb30 (score:0)
>         >     >>> >     Enabled on: Redund_CU2_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU3_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU5_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU1_WB30 (score:0)
>         >     >>> >   Resource: cu_5
>         >     >>> >     Enabled on: Redun_CU4_Wb30 (score:0)
>         >     >>> >     Enabled on: Redund_CU2_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU3_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU5_WB30 (score:0)
>         >     >>> >     Enabled on: Redund_CU1_WB30 (score:0)
>         >     >>> > Ordering Constraints:
>         >     >>> > Colocation Constraints:
>         >     >>> >   cu_3 with cu_2 (score:-INFINITY)
>         >     >>> >   cu_4 with cu_2 (score:-INFINITY)
>         >     >>> >   cu_4 with cu_3 (score:-INFINITY)
>         >     >>> >   cu_5 with cu_2 (score:-INFINITY)
>         >     >>> >   cu_5 with cu_3 (score:-INFINITY)
>         >     >>> >   cu_5 with cu_4 (score:-INFINITY)
>         >     >>> >
>         >     >>> > -Thanks
>         >     >>> > Nikhil
>         >     >>>
>         >     >>>
>         >     >>>
>         >
>         >     Hi,
>         >
>         >     use of utilization (balanced strategy) has one caveat:
>         resources are
>         >     not moved just because of utilization of one node is less,
>         when
>         >     nodes have the same allocation score for the resource.
>         >     So, after the simultaneus outage of two nodes in a 5-node
>         cluster,
>         >     it may appear that one node runs two resources and two
>         recovered
>         >     nodes run nothing.
>         >
>         >     Original 'utilization' strategy only limits resource
>         placement, it
>         >     is not considered when choosing a node for a resource.
>         >
>         >     Vladislav




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