[Gluster-users] performance/writebehind behavior

Anand Avati avati at gluster.org
Mon Jul 28 17:05:04 UTC 2014


Whether flush-behind is enabled or not, close() will guarantee all previous
write()s on that fd have been acknowledged by server. It is just the post
processing of close() itself which is performed in background when
flush-behind is enabled. The word "flush" here is probably confusing as it
is specific to FUSE terminology where an app triggered close() appears as a
flush fop.

Thanks


On Mon, Jul 28, 2014 at 9:58 AM, Richard van der Hoff <
richard at swiftserve.com> wrote:

> Would anyone be able to help out with this question?
>
> Thanks
>
> Richard
>
>
>
> On 11/07/14 00:08, Pranith Kumar Karampuri wrote:
>
>> CC write-behind Dev
>> On 07/10/2014 11:59 PM, Richard van der Hoff wrote:
>>
>>> Hi folks,
>>>
>>> Just wondering if anyone could clear up a question about expected
>>> behavior for the performance/writebehind translator.
>>>
>>> I'm using Gluster 3.3, with a single volume which is distributed to
>>> two bricks on a pair of servers. I have performance.flush-behind=off;
>>> the documentation [1] leads me to expect (but doesn't say explicitly)
>>> that this will make close() block until the write has been flushed -
>>> but that isn't consistent with the behaviour I'm seeing:
>>>
>>> $ dd if=/dev/zero of=/shared/vod/zero bs=1024 count=1000; wc -c
>>> /shared/vod/zero
>>> 1000+0 records in
>>> 1000+0 records out
>>> 1024000 bytes (1.0 MB) copied, 0.133975 s, 7.6 MB/s
>>> 1016832 /shared/vod/zero
>>>
>>> As you can see, the wc doesn't see all of the data which has been
>>> written by dd.
>>>
>>> If anyone could clear up whether or not this is expected, I'd be
>>> grateful.
>>>
>>> Thanks
>>>
>>> Richard
>>>
>>> [1]
>>> http://gluster.org/community/documentation/index.php/
>>> Translators/performance/writebehind
>>>
>>> _______________________________________________
>>> Gluster-users mailing list
>>> Gluster-users at gluster.org
>>> http://supercolony.gluster.org/mailman/listinfo/gluster-users
>>>
>>
>>
>
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