[Samba] kernel oplocks in ctdb environment

Bob Cregan bob.cregan at bristol.ac.uk
Fri Apr 1 01:58:57 MDT 2011

         Can anyone advise me on "kernel oplocks" in a ctdb cluster.

I have a ctdb (GPFS is the parallel file system) setup that uses samba 
(3.5.8) for cifs and IBM CNFS for NFS. Reading the documentation on 
kernel oplocks it seems to me that I can export the same area via samba 
and NFS with "kernel oplocks = Yes" .

My logic is that IBM CNFS has shared NFS locking information held on the 
shared filesystem, and therefore the kernel on each member of the ctdb 
cluster will be aware of any NFS locks. Samba with "kernel oplocks = 
Yes" should then not provide opportunistic locking to a CIFS client that 
want to access a file that has an NFS lock (giving an I/O error to that 

Is this in fact what will happen? The ability to dual export area of the 
filesystem would be very useful, but I don't want to risk data corruption.

Thanks for any advice.


Bob Cregan
Senior Storage Systems Administrator
Bristol University
Tel:     +44 (0) 117 331 4421
Mobile: +44 (0) 7712388129

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