[Gluster-users] Locking with GlusterFS

Robert Hajime Lanning lanning at lanning.cc
Mon Sep 9 20:01:50 UTC 2013

On 09/09/13 06:57, Olivier Desport wrote:
> Le 09/09/2013 10:50, Xavier Hernandez a écrit :
>> Al 09/09/13 09:59, En/na Olivier Desport ha escrit:
>>> Hello,
>>> I've created a distribued volume with two bricks. The shares are
>>> partitioned in XFS. Locking doesn't seem to be activated : when I
>>> write in the same file with two different clients, no error occurs.
>>> What option should I enable on the volume to enable locking ?
>> Locking is active always, however POSIX (the standard used by
>> GlusterFS) does not impose an exclusive access to files. Under POSIX,
>> it is the responsibility of the application to coordinate concurrent
>> accesses to files using explicit calls to fcntl() to coordinate them.
>> Even using this, another application can read/write the file if it
>> does no use an explicit call to fcntl().
>> Since GlusterFS is POSIX-compliant, it is the expected behavior that
>> two clients could write to the same file at the same time. The
>> resulting file may have a mix of writes from both clients.
>> Best regards,
>> Xavi
> Thanks for your answer.

BTW, the POSIX locking as described is called "Advisory Locking."

The locking you were originally expecting is called "Mandatory Locking."

Mr. Flibble
King of the Potato People

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