[Pacemaker] drbd diskless -> failover to other node

[Florian Haas]

On 2010-08-27 10:31, jimbob palmer wrote:
> 2010/8/27, Florian Haas <florian.haas at linbit.com>:
>> On 2010-08-26 16:43, jimbob palmer wrote:
>>> How can I configure pacemaker to failover when the primary node goes
>> diskless?
>>>
>>> Many thanks.
>>
>> man drbd.conf
>>
>> Look for the local-io-error handler and the on-io-error option.
>>
>> I doubt that it's a good idea to do this though; you're deliberately
>> foregoing a pretty handy DRBD feature there.
> 
> What do you mean? If the primary server loses it's disk, I'd like to
> switch to the server with a working disk.

Which means you're causing a service interruption when you don't need
to. Instead, your application could continue running on the same node,
DRBD will ensure that the application transparently writes to and reads
from the peer when it thinks it's writing locally, and you can coolly
hot-swap the drive out from under DRBD, and resync.

Usually service interruption is worse that degraded performance. Would
you rather fail over automatically, perhaps during peak hours and under
full load (which is what you are headed for), or would you rather have
your app continue to run where it is, to then switch over at a time of
your choosing?

Cheers,
Florian

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