SBD STONITH resource fail to start even when majority of the sbd disks (2 out of 3) are still accessible

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Environment

SUSE Linux Enterprise High Availability Extension 12
SUSE Linux Enterprise High Availability Extension 15

Situation

The SBD STONITH resource is configured with 3 sbd disks in the HA Cluster.
For example:

# crm configure show
...
primitive stonith-sbd stonith:external/sbd \
params pcmk_delay_max=30

# cat /etc/sysconfig/sbd
...
SBD_DEVICE="/dev/disk/by-id/scsi-DISK1;/dev/disk/by-id/scsi-DISK2;/dev/disk/by-id/scsi-DISK3"

It is observed that SBD STONITH resource fail to start if 1 sbd disk goes down.

Since majority of the sbd disks (2 out of 3) are still accessible, why does the SBD STONITH resource fail to start?

Resolution

This is the expected behaviour.

Cause

There is a misconception that since majority of the sbd disks (2 out of 3) are still accessible, the SBD STONITH resource should be allowed to start.
The SBD STONITH resource can only start successfully if all the sbd disks configured are accessible.

Status

Top Issue

Additional Information

However, if the SBD STONITH resource is already started and running with 3 disks, and if 1 disk suddenly goes down, then the SBD STONITH resource can still function properly.

Disclaimer

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