Setting up CTDB on OCFS2 and VMs ...

[Rowland Penny]

On 16/12/14 23:45, Martin Schwenke wrote:
> On Tue, 16 Dec 2014 21:12:12 +0000, Rowland Penny
> <repenny241155 at gmail.com> wrote:
>
>> I ran the ping_pong test this morning, following the wiki page and as
>> far as I could see it passed all tests.
> When I run "ping_pong /clusterfs/test.dat 3" on 1 node of a 2 node OCFS2
> cluster, I see a very high locking rate - in the 10000s.  When I run it
> on another node I see the same high locking rate and I don't see the
> rate drop on the 1st node.  That's a fail.

All I can say is that it did what the page said it would.

>
> This is on a cluster where I haven't worked out the extra steps to get
> lock coherence.
>
>> I have come to the conclusion that you need to be a CTDB dev to set CTDB
>> up, only they seem to have ALL the information required.
> Sorry, but that line is starting to grate.  I'm concerned that
> statements like this are likely to put people off using CTDB.  There are
> many non-CTDB-devs out there running CTDB with other cluster
> filesystems.

Sorry if what I said upsets you, but I have put a lot of time into 
trying to get this setup to work, but it seems to fail when I try to add 
CTDB.

> When the CTDB recovery lock is configured then CTDB has a hard
> requirement that the cluster filesystem *must* provide lock coherence.
> So the problem you have is a lack of lock coherence in OCFS2.

But it passes the ping_pong test.

> I am a CTDB dev.  I haven't yet got OCFS2 working, partly due to lack
> of time to figure out which pieces I'm missing.  I have a simple recipe
> that gets me to a similar point to where you are at and I haven't even
> looked at corosync.  At some time I will try to go through Richard's
> instructions and try to distill out the part that adds lock coherence.
>
> I was confused by the ping pong test results so I tried to clarify the
> documentation for that test.
>
> It seems like OCFS2 is stupendously difficult to setup with lock
> coherence.  This is not CTDB's fault.  Perhaps you need to be an OCFS2
> dev to setup CTDB with OCFS2?  ;-)

You could be right :-D
>> I absolutely give up, I cannot make it work, god knows I have tried, but
>> I just cannot make it work with the information available. I can find
>> bits here and bits there, but there still seems to be something missing,
>> or is it just me. Debian 7.7, Pacemaker, Corosync and Ocfs2 work OK, it
>> is just when you try to add CTDB.
> If all those other things provided lock coherence on the cluster
> filesystem then CTDB would work.  So adding CTDB makes you notice the
> problem but CTDB does not cause it.  :-)

I can well believe what you are saying, so it might help if CTDB could 
print something in the logs.

Rowland

>
> peace & happiness,
> martin