[Gluster-users] Gluster Questions from the Twitters

[Anand Avati]

On Thu, Nov 29, 2012 at 10:20 AM, Jeff Darcy <jdarcy at redhat.com> wrote:

> On 11/29/2012 10:14 AM, John Mark Walker wrote:
>
>>   from @saiweb :
>>
>> "@rackerhacker be warned unless it has been fixed NFS in gluster does not
>> distribute locks, multi node writes == split brain"
>>
>> https://twitter.com/Saiweb/**status/274114952963432449<https://twitter.com/Saiweb/status/274114952963432449>
>>
>
> Half true, or perhaps a matter of terminology.  AFAIK we don't have
> distributed locking, but the result of concurrent access would be
> inconsistency rather than (what we call) split brain.
>
>
>
Gluster NFS's locks (NLM) are just a "pass-through" translation to
posix-locks in the (appropriate) brick of the file. There is no need for
typical "distributed locking" as NFS is completely stateless. We should not
even be seeing even inconsistency if app is holding locks (even if app
instances are running on different nfs clients mounting off different NFS
heads).

BTW, NLM is available only in 3.3.x. If using 3.2.x there is no NFS locking
(clients forced to mount with -onolock) and there WILL be inconsistency
(but never split brain).

Avati
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