[DRBD-user] Any recommendations or cautions on using RAID under DRBD?

drbd at bobich.net drbd at bobich.net
Tue Mar 4 15:21:52 CET 2008

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

On Tue, 4 Mar 2008, Doug Knight wrote:

> I re-read my email after your response, and realized high availability
> is another big priority (hence our using heartbeat). My thought was that
> an initial drive failure in the RAID array should be handled within the
> current primary system, with DRBD/heartbeat fail-over as the next tier
> of failure recovery.

Do you really need a 2-tier system, though?

> Which brings up another question; how does DRBD
> handle RAID set failures? Obviously, a mirrored drive's failure would be
> transparent, but what about in the case of a striped set? Is there a way
> to determine that a striped set has failed and is in rebuild, and
> trigger DRBD to fail over to the secondary system where no rebuild is
> taking place? Maybe a Linux-HA question?

DRBD doesn't know and doesn't care if your RAID stripe is degraded or 
optimal. That's a job for something else. The underlying partition for 
DRBD is either there or isn't. There is nothing inbetween. If you want to 
fail over when the local RAID stripe is degraded, then you'll have to put 
in some external monitoring, possibly integrated with heartbeat. So yes, 
probably a Linux-HA question.

Also, do you plan to use this load-balanced or just fail-over/hot-spare?


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