On Mon, 2015-02-09 at 13:58 +0100, Peter P. wrote:
> Thank you. And what are the other two jobs ?
2) Collapse small writes.
if the write request is smaller, then it will collapse maximum up to
page size (128KB) .
3) Aggregate write requests
Aggregate one or more write request and send as a vectored write.
>
> I have set the write-behind-window-size to 500 Mb and wrote a 100 Mb
> file, but the speed is still the same.
> Can you explain why ?
Once we lied to application, then we will start processing the lied
list. So the entries will be deleted if one request is fulfilled. Though
it is a 100Mb write there is no need of the same window-size. Default
window-size is 1 MB. You can see the performance enhancement if you
turned-off the write-behind translator.
-Rafi KC
>
>
> Regards
>
> 2015-02-09 13:20 GMT+01:00 Peter P. <peter.prusi@xxxxxxxxxxxxxx>:
> Thank you. And what are the other two jobs ?
>
> I have set the write-behind-window-size to 500 Mb and wrote a
> 100 Mb file, but the speed is still the same.
> Can you explain why ?
>
>
> Regards
>
> Peter
>
>
> 2015-02-08 12:04 GMT+01:00 Rafi K C
> <muhammedrafi13@xxxxxxxxx>:
> On Sat, 2015-02-07 at 20:41 +0100, Peter Prusi wrote:
> > Hello,
> >
> > I'm new to glusterfs and I dont understand 'the
> > performance.write-behind-window-size' option. I'm
> using glusterfs 3.5.2
> > and setup a volume over two nodes connected over 1
> GbE.
> > Actually the write performance is about 58 Mb/s.
> This means glusterfs
> > writes the data simultaneous on both nodes. I'm
> trying to increase the
> > write speed and I thought this option would cache
> the data
> > on one node and then distribute to the other. So i
> could double the
> > speed. I played around with this option, but it has
> no effect to the
> > write speed.
>
> Write-behind does three jobs with respect to a
> write-request. One among
> them is,
>
> it will lie to application, which issued the
> write-request about the
> completion of write and then will perform this write
> operation in
> background. Basically, For a single inode, it will lie
> to the
> application until current size of the total lied
> request which are not
> fulfilled on nodes becomes equal to the window size.
> This size is
> configurable through
> performance.write-behind-window-size .
>
>
> > What am I doing wrong or
> > is there another tweak to increase the write
> > speed ?
>
> I'm not familiar with write performance tweaks. Some
> one more familiar
> with this can comment on this.
>
>
> Regards
> Rafi KC
> >
> > Thank you
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> >
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>
>
>
>
>
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