[DRBD-user] DRBD over RAID1 / Pacemaker failure detection

Florian Haas florian.haas at linbit.com
Tue Jun 1 17:47:34 CEST 2010

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On 2010-06-01 15:17, Caspar Smit wrote:
> I tested the following situation:
> 
> - I pulled out BOTH sdb and sdc on node 1.
> - Did a write action on the iscsitarget from a client machine.
> - DRBD (on-io-error detach) detached the primary node 1 and became:
>   Primary/Secondary - Diskless/UpToDate
> - The performance degraded significantly after it became diskless.
> 
> Is it possible for the Linbit OCF RA script to detect that a low level IO
> error occured on the DRBD backed storage (md0)?
> 
> What I would like is that in a case of low level failure (software raid
> failure) that a failover takes place and node 2 becomes the primary
> because now that doesn't happen.

It doesn't hurt to peruse the documentation. :)

http://www.drbd.org/users-guide/s-handling-disk-errors.html
http://www.drbd.org/users-guide/s-configure-io-error-behavior.html

If you use a local-io-error handler that simply does
"echo o > /proc/sysrq-trigger", then in case of an I/O error the node
will remove itself from the cluster and Pacemaker will initiate failover.

Cheers,
Florian

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