> -----Original Message-----
> From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com] On Behalf Of
> Jacek Jarosiewicz
> Sent: 20 August 2015 07:31
> To: Nick Fisk <n...@fisk.me.uk>; ceph-us...@ceph.com
> Subject: Re: [ceph-users] requests are blocked - problem
>
> On 08/19/2015 03:41 PM, Nick Fisk wrote:
> > Although you may get some benefit from tweaking parameters, I suspect
> you are nearer the performance ceiling for the current implementation of
> the tiering code. Could you post all the variables you set for the tiering
> including target_max_bytes and the dirty/full ratios.
> >
>
> sure, all the parameters set are like this:
>
> hit_set_type bloom
> hit_set_count 1
> hit_set_period 3600
> target_max_bytes 65498264640
> target_max_objects 1000000
> cache_target_full_ratio 0.95
> cache_min_flush_age 600
> cache_min_evict_age 1800
> cache_target_dirty_ratio 0.75
That pretty much looks ok to me, the only thing I can suggest is maybe to lower
the full_ratio a bit. The full ratio is based on the percentage across the
whole pool, but the actual eviction occurs at a percentage of a PG level. I
think this may mean that in certain cases a PG may block whilist is evicts even
though it appears the pool hasn't reached the full target.
>
>
> > Since you are doing maildirs, which will have lots of small files, you might
> also want to try making the object size of the RBD smaller. This will mean
> less
> data is needed to be shifted on each promotion/flush.
> >
>
> I'll try that - thanks!
>
> J
>
> --
> Jacek Jarosiewicz
> Administrator Systemów Informatycznych
>
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