[ClusterLabs] Antw: Re: Antw: [EXT] Re: Noticed oddity when DC is going to be fenced

Fri Mar 4 02:17:31 EST 2022

>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 02.03.2022 um 16:10 in
Nachricht
<dbc7cf19d29d2ce9227005b188af69160d386e7a.camel at redhat.com>:
> On Wed, 2022-03-02 at 08:41 +0100, Ulrich Windl wrote:
>> > > > Ken Gaillot <kgaillot at redhat.com> schrieb am 01.03.2022 um
>> > > > 16:04 in
>> Nachricht
>> <463458e414f7c411eb1107335be6ee9a6e2d13ee.camel at redhat.com>:
>> > On Tue, 2022‑03‑01 at 10:05 +0100, Ulrich Windl wrote:
>> > > Hi!
>> > > 
>> > > For current SLES15 SP3 I noticed an oddity when the node running
>> > > the
>> > > DC is going to be fenced:
>> > > It seems that another node is performing recovery operations
>> > > while
>> > > the old DC is not confirmed to be fenced.
>> > > 
>> > > Like this (116 is the DC):
>> > > Mar 01 01:33:53 h18 corosync[6754]:   [TOTEM ] A new membership
>> > > (172.20.16.18:45612) was formed. Members left: 116
>> > > 
>> > > Mar 01 01:33:53 h18 corosync[6754]:   [MAIN  ] Completed service
>> > > synchronization, ready to provide service.
>> > > Mar 01 01:33:53 h18 pacemaker‑controld[6980]:  notice: Our peer
>> > > on
>> > > the DC (h16) is dead
>> > > Mar 01 01:33:53 h18 pacemaker‑controld[6980]:  notice: State
>> > > transition S_NOT_DC ‑> S_ELECTION
>> > 
>> > At this point, h16 loses its DC status, so there is no DC
>> 
>> I agree from the perspective of h18, but does the DC (h16) know, too?
>> 
>> > > Mar 01 01:33:53 h18 dlm_controld[8544]: 394518 fence request 116
>> > > pid
>> > > 16307 nodedown time 1646094833 fence_all dlm_stonith
>> > > Mar 01 01:33:53 h18 pacemaker‑controld[6980]:  notice: State
>> > > transition S_ELECTION ‑> S_INTEGRATION
>> > 
>> > At this point, a new DC election has completed, and h18 is now the
>> > DC
>> > (as indicated by the scheduler messages later)
>> 
>> As above: Does h16 know at this point?
> 
> It doesn't matter, because the first thing the new DC will do is fence
> it. That's the beauty of fencing :)

I disagree:
When there are possibly multiple DCs active, fencing must ensure FIRST that
there is no other DC active BEFORE starting any action.
Just imagine two non-cluster filesystems on shared storage are mounted on two
different nodes concurrently.

Fencing the "other" DC at some later time does not help.

Regards,
Ulrich

> 
>> 
>> > > Mar 01 01:33:53 h18 dlm_stonith[16307]: stonith_api_time: Found 1
>> > > entries for 116/(null): 0 in progress, 0 completed
>> > > Mar 01 01:33:53 h18 pacemaker‑fenced[6973]:  notice: Client
>> > > stonith‑
>> > > api.16307.4961743f wants to fence (reboot) '116' with device
>> > > '(any)'
>> > > Mar 01 01:33:53 h18 pacemaker‑fenced[6973]:  notice: Requesting
>> > > peer
>> > > fencing (reboot) targeting h16
>> > > 
>> > > Mar 01 01:33:53 h18 pacemaker‑schedulerd[6978]:  warning: Cluster
>> > > node h16 will be fenced: peer is no longer part of the cluster
>> > > Mar 01 01:33:53 h18 pacemaker‑schedulerd[6978]:  warning: Node
>> > > h16 is
>> > > unclean
>> > > 
>> > > (so far, so good)
>> > > Mar 01 01:33:53 h18 pacemaker‑schedulerd[6978]:  warning:
>> > > Scheduling
>> > > Node h16 for STONITH
>> > > Mar 01 01:33:53 h18 pacemaker‑schedulerd[6978]:  notice:  * Fence
>> > > (reboot) h16 'peer is no longer part of the cluster'
>> > > 
>> > > Mar 01 01:33:53 h18 pacemaker‑controld[6980]:  notice: Initiating
>> > > monitor operation prm_stonith_sbd_monitor_600000 locally on h18
>> > > Mar 01 01:33:53 h18 pacemaker‑controld[6980]:  notice: Requesting
>> > > local execution of monitor operation for prm_stonith_sbd on h18
>> > > Mar 01 01:33:53 h18 pacemaker‑controld[6980]:  notice: Initiating
>> > > stop operation prm_cron_snap_v17_stop_0 on h19
>> > > (isn't h18 playing DC already while h16 isn't fenced yet?)
>> > > 
>> > > Mar 01 01:35:23 h18 pacemaker‑controld[6980]:  error: Node h18
>> > > did
>> > > not send monitor result (via controller) within 90000ms (action
>> > > timeout plus cluster‑delay)
>> > > Mar 01 01:35:23 h18 pacemaker‑controld[6980]:  error:
>> > > [Action   26]:
>> > > In‑flight resource op prm_stonith_sbd_monitor_600000 on h18
>> > > (priority: 9900, waiting: (null))
>> > > Mar 01 01:35:23 h18 pacemaker‑controld[6980]:  notice: Transition
>> > > 0
>> > > aborted: Action lost
>> > > Mar 01 01:35:23 h18 pacemaker‑controld[6980]:  warning: rsc_op
>> > > 26:
>> > > prm_stonith_sbd_monitor_600000 on h18 timed out
>> > > (whatever that means)
>> > > 
>> > > (now the fencing confirmation follows)
>> > > Mar 01 01:35:55 h18 pacemaker‑fenced[6973]:  notice: Operation
>> > > 'reboot' [16309] (call 2 from stonith‑api.16307) for host 'h16'
>> > > with
>> > > device 'prm_stonith_sbd' returned: 0 (OK)
>> > > Mar 01 01:35:55 h18 pacemaker‑fenced[6973]:  notice: Operation
>> > > 'reboot' targeting h16 on h18 for stonith‑api.16307 at h18.36b9a9bb:
>> > > OK
>> > > Mar 01 01:35:55 h18 stonith‑api[16307]: stonith_api_kick: Node
>> > > 116/(null) kicked: reboot
>> > > Mar 01 01:35:55 h18 pacemaker‑fenced[6973]:  notice: Operation
>> > > 'reboot' targeting h16 on rksaph18 for 
>> > > pacemaker‑controld.6980 at h18.8ce2f33f (merged): OK
>> > > Mar 01 01:35:55 h18 pacemaker‑controld[6980]:  notice: Peer h16
>> > > was
>> > > terminated (reboot) by h18 on behalf of stonith‑api.16307: OK
>> > > Mar 01 01:35:55 h18 pacemaker‑controld[6980]:  notice: Stonith
>> > > operation 2/1:0:0:a434124e‑3e35‑410d‑8e17‑ef9ae4e4e6eb: OK (0)
>> > > Mar 01 01:35:55 h18 pacemaker‑controld[6980]:  notice: Peer h16
>> > > was
>> > > terminated (reboot) by h18 on behalf of pacemaker‑controld.6980:
>> > > OK
>> > > 
>> > > (actual recovery happens)
>> > > Mar 01 01:35:55 h18 kernel: ocfs2: Begin replay journal (node
>> > > 116,
>> > > slot 0) on device (9,10)
>> > > 
>> > > Mar 01 01:35:55 h18 kernel: md: md10: resync done.
>> > > 
>> > > (more actions follow)
>> > > Mar 01 01:35:56 h18 pacemaker‑schedulerd[6978]:  notice:
>> > > Calculated
>> > > transition 1, saving inputs in
>> > > /var/lib/pacemaker/pengine/pe‑input‑
>> > > 87.bz2
>> > > 
>> > > (actions completed)
>> > > Mar 01 01:37:18 h18 pacemaker‑controld[6980]:  notice: State
>> > > transition S_TRANSITION_ENGINE ‑> S_IDLE
>> > > 
>> > > (pacemaker‑2.0.5+20201202.ba59be712‑150300.4.16.1.x86_64)
>> > > 
>> > > Did I misunderstand something, or does it look like a bug?
>> > > 
>> > > Regards,
>> > > Ulrich
>> > > 
>> > > 
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>> > ‑‑ 
>> > Ken Gaillot <kgaillot at redhat.com>
>> > 
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> -- 
> Ken Gaillot <kgaillot at redhat.com>
> 
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