[Drbd-dev] DRBD8: Split-brain false positive on Primary/primary potential patch

Philipp Reisner philipp.reisner at linbit.com
Thu Nov 16 10:10:25 CET 2006

Am Dienstag, 7. November 2006 00:47 schrieb Montrose, Ernest:
> When running Primary/Primary if the Heartbeat connection goes down when
> we recover we always split brain.  Simon had an idea which I have
> implemented. He is on vacation  so this may not reflect his exact idea.
> Essentially with this change, we do not create a new current UUID on the
> node unless I/O is seen. This prevent Split-Brain mitigation when both
> nodes are primary but only one node is originating I/O and never the
> other.  He is only stand-by in that case.
> Take a look and let me know.

Hi Ernest,

I understand your reasoning, I see the patch, which I guess does 
what you expect of it.

I do not want to do it that way for the following reasons:

 * It is only applicable in case you are using a 1-node filesystem
   on a primary-primary DRBD cluster.

   * I do not want users to do this. Because with this setup it is
     easily possible to mount the FS on both nodes concurrently.
     I want to protect the from themselfs ;)

   * Users using a 1-node filesystem should use DRBD withe 
     primary and secondary role.

 * I rather want to fix DRBD's split brain recovery methods to deal
   with a cluster crash of a primary-primary cluster (actually this
   is item 41 in the ROADMAP file)

I have a few hours time today, I will work on this today... 

: Dipl-Ing Philipp Reisner                      Tel +43-1-8178292-50 :
: LINBIT Information Technologies GmbH          Fax +43-1-8178292-82 :
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