[Ocfs2-users] ping_pong using o2cb and cman

[Dan Warner]

OK great, that made it clear. I didn't know that locking was a bit of a can
of worms after reading a few pages on in.

I did very quickly modify the ping_pong code to change the locking mechanism
to flock and the o2cb stack locks as expected producing slightly better
performance than cman.

>From http://wiki.samba.org/index.php/CTDB_Setup

OCFS2 1.4 offers cluster-wide byte-range locking, but the OCFS2 1.2
filesystem will need special handling, as it does not support cluster wide
byte range locking. To work around this you will need to use some other sort
of shared filesystem (such as NFS) for the "private directory" in Samba and
the CTDB_RECOVERY_LOCK file in CTDB.

So I take it that to use samba ocfs2 you need to use cman or pacemaker as
they support byte range locking or as suggested above use NFS for certain
directories and the o2cb stack

Thanks for your time, Dan

On 18 January 2011 19:06, Sunil Mushran <sunil.mushran at oracle.com> wrote:

>  fcntl() locking does not pair at all with dlm locking. So both ocfs2 and
> gfs2
> use a special scheme just for this lock. Both use the ordered messaging
> provided by the corosync cluster engine. This lock is fully synchronised
> and
> thus is not as performant as it can be. (Both cman and pacemaker use cce.)
>
> But that's ok because fcntl()'s locking semantics is not what you think it
> is.
> The lock is almost useless in this day and age. The only use is supporting
> legacy apps. For more refer to Jeremy Allison's overview of this user lock.
> http://www.samba.org/samba/news/articles/low_point/tale_two_stds_os2.html
>
> Given that and considering most apps allow users to choose between fcntl()
> and flock(), we've decided for now to just support the latter with o2cb.
>
> flock() pairs well with dlm locking.
>
>
> On 01/18/2011 10:22 AM, Dan Warner wrote:
>
> OK thanks for the clarification.
>
> Is the support of fcntl() locking within o2cb, on the wishlist of features
> to be implemented at a future date? Is it even a priority to do?
>
> Thanks, Dan
>
>  On 18 January 2011 18:00, Sunil Mushran <sunil.mushran at oracle.com> wrote:
>
>>  ping_long tests the fcntl() user locks.
>>
>> ocfs2 supports clustered fcntl() locking with cman and pacemaker
>> cluster stacks. Not with o2cb.
>>
>> ocfs2 supports clustered flock() with all stacks. o2cb, cman and
>> pacemaker.
>>
>
>
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>
>
>
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