[Linux-cluster] Two cluster nodes hold exclusive POSIX lock on the same file

Vladimir Martinek vm at sykora.cz
Mon Nov 2 08:34:25 UTC 2015

Thank you,

understood it is working as expected. But how is it ensured that the two 
nodes holding the lock can't write
to the same file then?

Thank you

Vladimir Martinek

On 10/30/2015 09:12 PM, David Teigland wrote:
> On Fri, Oct 30, 2015 at 03:04:34PM +0100, Vladimir Martinek wrote:
>> Hello,
>> I have a 3 node cluster and fencing agent that takes about 30
>> seconds to complete the fencing. In those 30 seconds it is possible
>> for two nodes of the cluster to get exclusive POSIX lock on the same
>> file.
>> Did I miss something here or is this correct behaviour?
>> Also, when trying with BSD flock, it works as I would expect - the
>> locks are only released after the fencing completes and node 1 is
>> confirmed to be fenced.
>> Following is output of dlm_tool dump command. Watch for the line
>> "gfs2fs purged 1 plocks for 1" - the locks of failed node 1 are
>> purged long before the fencing is completed.
>> Thank you for any advice.
> It works as expected; recovery of posix locks does not need to wait for
> fencing to complete.
> Dave


*Ing. Vladimír Martinek*

T: +420 723 908 968
@: vm at sykora.cz

Sykora Data Center s.r.o.
28. října 1512/123, 702 00 Ostrava

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