On Fri, Apr 01, 2011 at 08:58:57AM +0100, Bob Cregan wrote: > Hi > 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 client??).
The only point of kernel oplocks is to be informed if someone else wants to open a file. We can then inform the client to flush its cache and not cache future requests. Intra-Samba this works in cooperation with GPFS. GPFS has a special leases API that Samba can make use of with the gpfs VFS module, so the theory is that oplocks should work cross-protocol. I haven't run concrete tests in that area for a while though, I'd need to do that again to be 100% certain nothing broke. Volker -- SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen phone: +49-551-370000-0, fax: +49-551-370000-9 AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba