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Re: [linux-lvm] LVM snapshot with Clustered VG



Am 06.03.13 14:28, schrieb Vladislav Bogdanov:
06.03.2013 15:17, Andreas Pflug wrote:
Am 06.03.13 12:20, schrieb Vladislav Bogdanov:
I'm running corosync 1.4.2 (debian wheezy).
Which cluster manager interface does clvmd detect? corosync or openais?
You should use former, openais one is(was) using LCK service which is
very unstable.
It's using openais. I'm not too happy about the stability, so maybe I'd
switch to corosync now.
That could be the problem btw. I did neither test nor look at openais
module implementation in clvmd, because I had plenty problems with it
(actually with LCK under it) in the past, so I even forced to use
corosync (CPG) + dlm instead of detected openais (CPG+LCK) for older
systems (look at -I switch of clvmd).

And, openais is deprecated upstream, so I do not see any reason to use
it. Even gfs_controld (which is probably the only well-known user of
openais services) actually does not strictly require it, at least I was
able to port it to pure CPG+DLM with dlm4 on top of corosync2, which is
not compatible with openais plugins.

Also you may need quorum patch found in this list, it does its job well.

Could this be a reason for the x-lock failure as well?
You just answered the quirky question :-)

Unfortunately, corosync/dlm don't work for me as expected. When starting
clvmd -I corosync (with dlm kernel module loaded), creating the dlm
lockspace "clvmd" fails, with

dlm: no local IP address has been set
dlm: cannot start dlm lowcomms -107

You need to have dlm_controld running on all nodes.
And that is not trivial with corosync1. You need to either use cman or
use deprecated dlm_controld.pcmk which was removed from a cluster (cman)
package after 3.0.17. Latter does not work well without heavy patching
(http://www.mail-archive.com/pacemaker oss clusterlabs org/msg09959.html
,
http://www.mail-archive.com/pacemaker oss clusterlabs org/msg11123.html
and
http://oss.clusterlabs.org/pipermail/pacemaker/2012-February/013073.html).
Even after that there are some problems with it.

Latest versions (4.x) of dlm (it was split from cman) work fine with
corosync2 and pacemaker 1.1.6+. But I doubt it can ever be compiled with
corosync1. Yes, it cannot, because it requires quorum which appeared in
corosync2.

You may look at thread
http://oss.clusterlabs.org/pipermail/pacemaker/2012-October/015826.html
for some info.

That's all why I moved to corosync2. You can search through pacemaker
list archives for dlm-related messages from me to get full picture.

You may also look at slides I presented at LVEE winter 2013:
http://lvee.org/uploads/image_upload/file/267/Linux_Clusters_at_LVEE_2013.pdf

Thanks for the pointers, seems there's no way around reorganizing all clustering stuff.

Regards,
Andreas


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