[DRBD-user] secondary sync behaviour after drbd stop and start

Felix Frank ff at mpexnet.de
Wed Jun 22 09:41:27 CEST 2011


Hi,

On 06/22/2011 08:29 AM, Gianluca Cecchi wrote:
> Certainly it is not my intention to bypass DRBD. In fact in my e-mail

yet that is what you inadvertantly did. DRBD has no possible way of
finding out that you messed with its backing storage. Well, except you
do an online verify, which is expensive.

> I tried to clarify that it was a simulation of changed data before
> resync.

This can happen if the "remote" side becomes Primary while disconnected.
The result is a split-brain, which must be resolved one way or another
(usually by human intervention - you get to decide whose changes should
get trashed). See
http://www.drbd.org/users-guide/s-resolve-split-brain.html.

Again: If someone decides to mess with DRBD *backing storage*, chances
are it will never be detected unless you run verify.

> b)
> drbdadm invalidate-remote r0

Sure, fencing your peer is a way of safe-guarding yourself against
split-brain.

HTH,
Felix



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