[ClusterLabs] Questions about SBD behavior
Andrei Borzenkov
arvidjaar at gmail.com
Fri May 25 06:44:36 EDT 2018
On Fri, May 25, 2018 at 10:08 AM, Klaus Wenninger <kwenning at redhat.com> wrote:
> On 05/25/2018 07:31 AM, 井上 和徳 wrote:
>> Hi,
>>
>> I am checking the watchdog function of SBD (without shared block-device).
>> In a two-node cluster, if one cluster is stopped, watchdog is triggered on the remaining node.
>> Is this the designed behavior?
>
> SBD without a shared block-device doesn't really make sense on
> a two-node cluster.
> The basic idea is - e.g. in a case of a networking problem -
> that a cluster splits up in a quorate and a non-quorate partition.
> The quorate partition stays over while SBD guarantees a
> reliable watchdog-based self-fencing of the non-quorate partition
> within a defined timeout.
Does it require no-quorum-policy=suicide or it decides completely
independently? I.e. would it fire also with no-quorum-policy=ignore?
> This idea of course doesn't work with just 2 nodes.
> Taking quorum info from the 2-node feature of corosync (automatically
> switching on wait-for-all) doesn't help in this case but instead
> would lead to split-brain.
So what you are saying is that SBD ignores quorum information from
corosync and takes its own decisions based on pure count of nodes. Do
I understand it correctly?
> What you can do - and what e.g. pcs does automatically - is enable
> the auto-tie-breaker instead of two-node in corosync. But that
> still doesn't give you a higher availability than the one of the
> winner of auto-tie-breaker. (Maybe interesting if you are going
> for a load-balancing-scenario that doesn't affect availability or
> for a transient state while setting up a cluste node-by-node ...)
> What you can do though is using qdevice to still have 'real-quorum'
> info with just 2 full cluster-nodes.
>
> There was quite a lot of discussion round this topic on this
> thread previously if you search the history.
>
> Regards,
> Klaus
>
>>
>> [vmrh75b]# cat /etc/corosync/corosync.conf
>> (snip)
>> quorum {
>> provider: corosync_votequorum
>> two_node: 1
>> }
>>
>> [vmrh75b]# cat /etc/sysconfig/sbd
>> # This file has been generated by pcs.
>> SBD_DELAY_START=no
>> ## SBD_DEVICE="/dev/vdb1"
>> SBD_OPTS="-vvv"
>> SBD_PACEMAKER=yes
>> SBD_STARTMODE=always
>> SBD_WATCHDOG_DEV=/dev/watchdog
>> SBD_WATCHDOG_TIMEOUT=5
>>
>> [vmrh75b]# crm_mon -r1
>> Stack: corosync
>> Current DC: vmrh75a (version 2.0.0-0.1.rc4.el7-2.0.0-rc4) - partition with quorum
>> Last updated: Fri May 25 13:36:07 2018
>> Last change: Fri May 25 13:35:22 2018 by root via cibadmin on vmrh75a
>>
>> 2 nodes configured
>> 0 resources configured
>>
>> Online: [ vmrh75a vmrh75b ]
>>
>> No resources
>>
>> [vmrh75b]# pcs property show
>> Cluster Properties:
>> cluster-infrastructure: corosync
>> cluster-name: my_cluster
>> dc-version: 2.0.0-0.1.rc4.el7-2.0.0-rc4
>> have-watchdog: true
>> stonith-enabled: false
>>
>> [vmrh75b]# ps -ef | egrep "sbd|coro|pace"
>> root 2169 1 0 13:34 ? 00:00:00 sbd: inquisitor
>> root 2170 2169 0 13:34 ? 00:00:00 sbd: watcher: Pacemaker
>> root 2171 2169 0 13:34 ? 00:00:00 sbd: watcher: Cluster
>> root 2172 1 0 13:34 ? 00:00:00 corosync
>> root 2179 1 0 13:34 ? 00:00:00 /usr/sbin/pacemakerd -f
>> haclust+ 2180 2179 0 13:34 ? 00:00:00 /usr/libexec/pacemaker/pacemaker-based
>> root 2181 2179 0 13:34 ? 00:00:00 /usr/libexec/pacemaker/pacemaker-fenced
>> root 2182 2179 0 13:34 ? 00:00:00 /usr/libexec/pacemaker/pacemaker-execd
>> haclust+ 2183 2179 0 13:34 ? 00:00:00 /usr/libexec/pacemaker/pacemaker-attrd
>> haclust+ 2184 2179 0 13:34 ? 00:00:00 /usr/libexec/pacemaker/pacemaker-schedulerd
>> haclust+ 2185 2179 0 13:34 ? 00:00:00 /usr/libexec/pacemaker/pacemaker-controld
>>
>> [vmrh75b]# pcs cluster stop vmrh75a
>> vmrh75a: Stopping Cluster (pacemaker)...
>> vmrh75a: Stopping Cluster (corosync)...
>>
>> [vmrh75b]# tail -F /var/log/messages
>> May 25 13:37:00 vmrh75b pacemaker-controld[2185]: notice: Our peer on the DC (vmrh75a) is dead
>> May 25 13:37:00 vmrh75b pacemaker-controld[2185]: notice: State transition S_NOT_DC -> S_ELECTION
>> May 25 13:37:00 vmrh75b pacemaker-controld[2185]: notice: State transition S_ELECTION -> S_INTEGRATION
>> May 25 13:37:00 vmrh75b pacemaker-attrd[2183]: notice: Node vmrh75a state is now lost
>> May 25 13:37:00 vmrh75b pacemaker-attrd[2183]: notice: Removing all vmrh75a attributes for peer loss
>> May 25 13:37:00 vmrh75b pacemaker-attrd[2183]: notice: Lost attribute writer vmrh75a
>> May 25 13:37:00 vmrh75b pacemaker-attrd[2183]: notice: Purged 1 peer with id=1 and/or uname=vmrh75a from the membership cache
>> May 25 13:37:00 vmrh75b pacemaker-fenced[2181]: notice: Node vmrh75a state is now lost
>> May 25 13:37:00 vmrh75b pacemaker-fenced[2181]: notice: Purged 1 peer with id=1 and/or uname=vmrh75a from the membership cache
>> May 25 13:37:00 vmrh75b pacemaker-based[2180]: notice: Node vmrh75a state is now lost
>> May 25 13:37:00 vmrh75b pacemaker-based[2180]: notice: Purged 1 peer with id=1 and/or uname=vmrh75a from the membership cache
>> May 25 13:37:00 vmrh75b pacemaker-controld[2185]: warning: Input I_ELECTION_DC received in state S_INTEGRATION from do_election_check
>> May 25 13:37:01 vmrh75b sbd[2171]: cluster: warning: set_servant_health: Connected to corosync but requires both nodes present
>> May 25 13:37:01 vmrh75b sbd[2171]: cluster: warning: notify_parent: Notifying parent: UNHEALTHY (6)
>> May 25 13:37:01 vmrh75b sbd[2169]: warning: inquisitor_child: cluster health check: UNHEALTHY
>> May 25 13:37:01 vmrh75b sbd[2169]: warning: inquisitor_child: Servant cluster is outdated (age: 226)
>> May 25 13:37:01 vmrh75b sbd[2170]: pcmk: notice: unpack_config: Watchdog will be used via SBD if fencing is required
>> May 25 13:37:01 vmrh75b sbd[2170]: pcmk: info: determine_online_status: Node vmrh75b is online
>> May 25 13:37:01 vmrh75b sbd[2170]: pcmk: info: unpack_node_loop: Node 2 is already processed
>> May 25 13:37:01 vmrh75b sbd[2170]: pcmk: info: unpack_node_loop: Node 2 is already processed
>> May 25 13:37:01 vmrh75b sbd[2171]: cluster: warning: notify_parent: Notifying parent: UNHEALTHY (6)
>> May 25 13:37:01 vmrh75b corosync[2172]: [TOTEM ] A new membership (192.168.28.132:5712) was formed. Members left: 1
>> May 25 13:37:01 vmrh75b corosync[2172]: [QUORUM] Members[1]: 2
>> May 25 13:37:01 vmrh75b corosync[2172]: [MAIN ] Completed service synchronization, ready to provide service.
>> May 25 13:37:01 vmrh75b pacemakerd[2179]: notice: Node vmrh75a state is now lost
>> May 25 13:37:01 vmrh75b pacemaker-controld[2185]: notice: Node vmrh75a state is now lost
>> May 25 13:37:01 vmrh75b pacemaker-controld[2185]: warning: Stonith/shutdown of node vmrh75a was not expected
>> May 25 13:37:02 vmrh75b sbd[2171]: cluster: warning: notify_parent: Notifying parent: UNHEALTHY (6)
>> May 25 13:37:02 vmrh75b pacemaker-schedulerd[2184]: notice: Watchdog will be used via SBD if fencing is required
>> May 25 13:37:02 vmrh75b pacemaker-schedulerd[2184]: warning: Blind faith: not fencing unseen nodes
>> May 25 13:37:02 vmrh75b pacemaker-schedulerd[2184]: notice: Delaying fencing operations until there are resources to manage
>> May 25 13:37:02 vmrh75b pacemaker-schedulerd[2184]: notice: Calculated transition 0, saving inputs in /var/lib/pacemaker/pengine/pe-input-1410.bz2
>> May 25 13:37:02 vmrh75b pacemaker-controld[2185]: notice: Transition 0 (Complete=0, Pending=0, Fired=0, Skipped=0, Incomplete=0, Source=/var/lib/pacemaker/pengine/pe-input-1410.bz2): Complete
>> May 25 13:37:02 vmrh75b pacemaker-controld[2185]: notice: State transition S_TRANSITION_ENGINE -> S_IDLE
>> May 25 13:37:03 vmrh75b sbd[2171]: cluster: warning: notify_parent: Notifying parent: UNHEALTHY (6)
>> May 25 13:37:03 vmrh75b sbd[2170]: pcmk: notice: unpack_config: Watchdog will be used via SBD if fencing is required
>> May 25 13:37:03 vmrh75b sbd[2170]: pcmk: info: determine_online_status: Node vmrh75b is online
>> May 25 13:37:03 vmrh75b sbd[2170]: pcmk: info: unpack_node_loop: Node 2 is already processed
>> May 25 13:37:03 vmrh75b sbd[2170]: pcmk: info: unpack_node_loop: Node 2 is already processed
>> May 25 13:37:04 vmrh75b sbd[2171]: cluster: warning: notify_parent: Notifying parent: UNHEALTHY (6)
>> May 25 13:37:05 vmrh75b sbd[2169]: warning: inquisitor_child: Latency: No liveness for 4 s exceeds threshold of 3 s (healthy servants: 0)
>> May 25 13:37:05 vmrh75b sbd[2171]: cluster: warning: notify_parent: Notifying parent: UNHEALTHY (6)
>> May 25 13:37:05 vmrh75b sbd[2169]: warning: inquisitor_child: Latency: No liveness for 4 s exceeds threshold of 3 s (healthy servants: 0)
>>
>> Best Regards,
>> Kazunori INOUE
>> _______________________________________________
>> Users mailing list: Users at clusterlabs.org
>> https://lists.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
>
> _______________________________________________
> Users mailing list: Users at clusterlabs.org
> https://lists.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
More information about the Users
mailing list