Re: bad performance fio random write - rados bench random write to compare?

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 02.07.2012 21:52, schrieb Gregory Farnum:
> On Tue, Jun 19, 2012 at 7:05 AM, Alexandre DERUMIER <aderumier@odiso.com> wrote:
>> Hi,
>> Is it possible to do random write bench with rados bench command ?
>>
>> I have very base random write performance with 4K block size inside qemu-kvm,
>> 1000 iops/s max with 3 nodes with 3x 5 disk 15k
>> (Maybe it's related to my constant disk writes, like datas are not flushed sequentially to disk)
>>
>> seekwatcher movie of 1 osd here :
>> http://odisoweb1.odiso.net/random-write-4k.mpg
>>
>> I would like to do tests on kvm host with rados command to compare.
>> (I don't have rbd module in my kvm host kernel,so I can't use fio on the host)
>
> Unfortunately, nobody's implemented a random write test in rados bench
> yet (this might be a good bug for somebody who's interested in getting
> in to the project — rados bench is pretty simple). I'd offer more
> suggestions but I think we've already discussed this elsewhere. :)

I think random I/O is very important for a lot of people at least for 
people using KVM on top of ceph. Sadly i can't implement it.

Stefan
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