[ClusterLabs] DRBD split-brain investigations, automatic fixes and manual intervention...

[Andrei Borzenkov]

On 20.10.2021 17:54, Ian Diddams wrote:
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>     On Wednesday, 20 October 2021, 11:15:48 BST, Andrei Borzenkov <arvidjaar at gmail.com> wrote:  
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>> You cannot resolve split brain without fencing. This is as simple as
>> that. Your pacemaker configuration (from another mail) shows
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>> pcs -f clust_cfg property set stonith-enabled=false
>> pcs -f clust_cfg property set no-quorum-policy=ignore
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>> This is a recipe for data corruption.
> Thanks Andrei - I appreciate your feedback.  So the obvious question form this bloke that trying to get up to speed etc etc is
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> ...  how do i set up fencing to
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It depends on what hardware you have. For physical systems IPMI may be
available or managed power outlets; both allow cutting power to another
node over LAN.

For virtual machines you may use fencing agent that contacts hypervisor
or management instance (like vCenter).

There is also SBD, it requires shared storage. Third node with iSCSI
target may do it.

Qdevice with watchdog may be an option.

Personally I prefer SBD which is the most hardware-agnostic solution.

> * avoid data corruption
> * enable automatic resolution of split-brains?
> 
> cheers
> ian
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