Re: Newstore Update Part 2

[Mark Nelson <mnelson@redhat.com>]

On 05/08/2015 07:19 PM, Gregory Farnum wrote:
> On Fri, May 8, 2015 at 4:21 PM, Mark Nelson <mnelson@redhat.com> wrote:
>> Hi Guys,
>>
>> At the performance meeting this week we discussed the possibility of
>> changing how newstore handles large partial overwrites.
>
> Er, what was the potential change?

Basically breaking the object up into fragments on overwrite so that we 
don't do big updates to 4MB files behind the scenes.  Instead for 
overwrites of a certain size (say 1MB+) create a new fragment.

>
>> To determine if
>> this is useful, we look at rados bench and rbd performance of newstore at
>> various IO sizes.  I've also included some rados bench read results as folks
>> were interested in those.  On the graphs I've tried to mark interesting
>> improvements/regressions and also some questions/comments. These tests were
>> run without overlay which may help small IO performance in some cases.
>>
>> Graphs are here:
>>
>> http://nhm.ceph.com/newstore/8c8c5903_rbd_rados_tests.pdf
>>
>> Thanks,
>> Mark
>> --
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