Setting up CTDB on OCFS2 and VMs ...

[Rowland Penny]

On 02/01/15 22:07, Martin Schwenke wrote:
> On Fri, 02 Jan 2015 12:57:14 +0000, Rowland Penny
> <repenny241155 at gmail.com> wrote:
>
>> OK, the lockfile now seems to work, at least I have a setting in
>> /etc/default/ctdb and both nodes are OK.
>>
>> How have I managed this: well after reading something on a google link,
>> I did something, changed where 'CTDB_RECOVERY_LOCK' pointed to and it
>> now works.
>>
>> What did I do???
>>
>> I INSTALLED AND SETUP AN NFS SERVER ON ONE OF THE NODES!!!
>>
>> Great, to use ctdb and samba (which is a way to share files), you have
>> to set up a separate way of sharing files.
> Please stop.  You're embarrassing yourself and you're spreading
> misinformation that people will find when they search for information
> about running CTDB with OCFS2.
>
> What you say is simply not true, apart from that fact that you need
> lock coherency between the nodes to be able to use the recovery lock.
> You have simply hacked a workaround that can apparently make the
> recovery lock work.  To make the recovery lock work properly your
> cluster filesystem needs lock coherency.  We have already discussed this
> several weeks ago:
>
>    https://lists.samba.org/archive/samba-technical/2014-December/104426.html
>
> Nothing has changed.

Yes, nothing has changed, the ping_pong test works just like the wiki 
page says it should, so if you are saying that the test is unreliable, 
then so be it.


>
> It appears that getting lock coherency to work in OCFS2 is staggeringly
> difficult.  Unfortunately, apart from Richard's work, we have no recipe
> for setting up OCFS2 with lock coherence.  We can't tell you what
> is wrong with your cluster except that CTDB's lock coherence test for
> the recovery lock is failing.  Perhaps this is a topic that should be
> taken to an OCFS2 mailing list?

Why? as far as I can see (and from the information I can find) 
everything works until I try to get ctdb to set the lockfile. I then 
find a post that said set the lock on an NFS shared directory, I do this 
and the two nodes are now both OK and you are telling me that what I am 
doing is wrong and blaming it on OCFS2, but will not or cannot tell me 
what is wrong.

>
> How about we leave it at that and stop beating up on CTDB because a
> particular filesystem doesn't (easily) provide a prerequisite feature?

I will say it again, everything seems to work ok until you set 
'CTDB_RECOVERY_LOCK' to be on the samba share on the cluster, but if you 
set it on a NFS share it seems to work.

>
> We'll update CTDB so that it logs a clear message and aborts when the
> lock coherence check fails during the first recovery.
>
> Until then:
>
>    http://dilbert.com/strips/comic/1995-06-24/
>
> but s/computer/cluster filesystem/  - that is, why don't you try a
> different cluster filesystem?  ;-)

OK, I give in, I will stop trying to use your software with ocfs2
> peace & happiness,
> martin