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

David Teigland teigland at redhat.com
Fri Oct 30 20:12:22 UTC 2015

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.

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