Re: performance/writebehind behavior

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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@xxxxxxxxxxxxxx> 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

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