Re: poor OSD performance using kernel 3.4

[Mark Nelson <mark.nelson@inktank.com>]

On 05/24/2012 02:05 PM, Stefan Priebe wrote:
> Am 24.05.2012 20:53, schrieb Mark Nelson:
>> Hi Stefan,
>>
>> Thanks for the info! I've been testing on 3.4 for the last couple of
>> days but haven't run into that problem here. It looks like your journal
>> has writes going to it quickly and then things stall as it tries to
>> write out to your data disk.
> That's a good point. Right now while testing i'm using a tmpfs ramdisk 
> for the journal and have set journal dio = false in ceph.conf? Might 
> this be the difference / problem?
>
> 3.2.18 works fine too.

Honestly I don't know if tmpfs journal with dio = false would lead to 
that kind of behavior.  Anything interesting in the logs if you turn 
debugging up?

>
> > I wonder if any of the data actually makes
>> it to the disk... Can you run iostat or collectl or something and see
>> what kind of write throughput you get to the OSD data disks?
> none... so it seems get's never transferred from journal to disk.

This might be a stupid question, but writes to those partitions work 
outside of Ceph with the new kernel right?

>
> Stefan

Thanks,
Mark