[DRBD-user] Using discard-zero-changes and consensus with fencing

Lars Ellenberg lars.ellenberg at linbit.com
Thu Feb 26 14:33:48 CET 2009

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


On Thu, Feb 26, 2009 at 10:42:20AM +0100, Federico Simoncelli wrote:
> Hi all I'm using drbd 8.3.0 with fence configured for my resources and
> I'd like to use discard-zero-changes for after-sb-0pri and consensus
> for after-sb-1pri; the problem is that when a node fence the other
> looks like that they both create a new UUID and the
> discard-zero-changes doesn't work. Is my analysis correct? Is there
> something wrong in my configuration?

you have _two primaries_
the new UUID is created when connection is lost.

when the connection is first re-established,
they are both still Primary, they have diverging data sets:
=> split brain is detected.

after-sb-2pri would be the setting that is used here
(_2_ primaries, when split brain is detected)

and they certainly do not reach a consensus:

> Feb 26 09:58:32 node2 kernel: drbd0: Split-Brain detected, dropping connection!

there is no easy way out.

the only way out it to hard-reset one node,
let it come up as secondary, become synctarget,
and only then "activate" it again.

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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