----- Message from Sage Weil <sweil at redhat.com> ---------
Date: Thu, 31 Jul 2014 08:51:34 -0700 (PDT)
From: Sage Weil <sweil at redhat.com>
Subject: Re: cache pool osds crashing when data is
evicting to underlying storage pool
To: Kenneth Waegeman <Kenneth.Waegeman at UGent.be>
Cc: ceph-users <ceph-users at lists.ceph.com>
> Hi Kenneth,
>
> On Thu, 31 Jul 2014, Kenneth Waegeman wrote:
>> Hi all,
>>
>> We have a erasure coded pool 'ecdata' and a replicated pool 'cache'
>> acting as
>> writeback cache upon it.
>> When running 'rados -p ecdata bench 1000 write', it starts filling up the
>> 'cache' pool as expected.
>> I want to see what happens when it starts evicting, therefore I've done:
>> ceph osd pool set cache target_max_bytes $((200*1024*1024*1024))
>>
>> When it start to evict the objects to 'ecdata', the cache osds are all
>> crashing. I logged an issue : http://tracker.ceph.com/issues/8982
>>
>> I enabled the cache with this commands:
>>
>> ceph osd pool create cache 1024 1024
>> ceph osd erasure-code-profile set profile11 k=8 m=3
>> ruleset-failure-domain=osd
>> ceph osd pool create ecdata 128 128 erasure profile11
>>
>> ceph osd tier add ecdata cache
>> ceph osd tier cache-mode cache writeback
>> ceph osd tier set-overlay ecdata cache
>>
>> Is there something else that I should configure?
>
> I think you just need to enable the hit_set tracking. It's
> obviously not supposed to crash when you don't, though; I'll fix
> that up shortly.
Thanks, it seems to work now! I saw the values of hit_set_count,.. are
set to zero. What does this mean? Is this the default value or does it
actually mean '0' (and then they should be set always?)
>
> By the way, although we love the testing on the development releases, you
> probably want to be using firefly if this is destined for production.
We are still in testing phase, so we can keep working with the
development releases :-)
>
> Thanks!
> sage
----- End message from Sage Weil <sweil at redhat.com> -----
--
Met vriendelijke groeten,
Kenneth Waegeman
