[DRBD-user] DRBD + OCFS2 - Split-Brain detected but unresolved

Felix Frank ff at mpexnet.de
Tue Apr 17 18:31:09 CEST 2012

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


Hi,

On 04/17/2012 05:06 PM, Jacek Osiecki wrote:
> automatic recovery sometimes works and sometimes does
> not.

we seem to be lacking your drbd config. How is automatic split brain
recovery configured?
I get the feeling it's not. What split-brain situations have you
perceived as being automatically solved?

> 73E08E8E06754D97:A9BC3587FC5AA879:0BF8587A4ABA37B5:0BF7587A4ABA37B5
> bits:0 flags:0

This looks fine - the peer has set 0 bits, so it's probably indeed
unchanged.

> why the case isn't solved, since second server doesn't write to drbd0,
> sometimes even partition wasn't mounted (I can't be 100% sure, but it
> seems so).

A policy of discard-zero-changes could solve this for you, but only if
configured thus.

> I would be greatful if you could give me some hint how to make this
> configuration stable, without sacrificing data on one of nodes (now in
> order to recover I have to set second node to slave). Any ideas what is
> wrong in my setup?

Your config would be ultra helpful :-)

> P.S. Any suggestions how to measure real performance (read/write/copy)
> of DRBD+OCFS2? UnixBench gives crazy results (read performance about 10%
> of local filesystem)...

Is this crazy? I wouldn't know. But bear in mind that stat can be an
expensive operation on a cluster file system vs. a regular old fs.

HTH,
Felix



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