Sam,
We are seeing some good client IO results during recovery by using the 
following values..

osd recovery max active = 1
osd max backfills = 1
osd recovery threads = 1
osd recovery op priority = 1

It is all flash though.  The recovery time in case of entire node (~120 TB) 
failure/a single drive (~8TB) failure is also not too bad with the above 
settings.

Thanks & Regards
Somnath

-----Original Message-----
From: ceph-devel-ow...@vger.kernel.org 
[mailto:ceph-devel-ow...@vger.kernel.org] On Behalf Of Samuel Just
Sent: Friday, May 29, 2015 2:47 PM
To: ceph-devel; 'ceph-users@lists.ceph.com' (ceph-users@lists.ceph.com)
Subject: Discuss: New default recovery config settings

Many people have reported that they need to lower the osd recovery config 
options to minimize the impact of recovery on client io.  We are talking about 
changing the defaults as follows:

osd_max_backfills to 1 (from 10)
osd_recovery_max_active to 3 (from 15)
osd_recovery_op_priority to 1 (from 10)
osd_recovery_max_single_start to 1 (from 5)

We'd like a bit of feedback first though.  Is anyone happy with the current 
configs?  Is anyone using something between these values and the current 
defaults?  What kind of workload?  I'd guess that lowering osd_max_backfills to 
1 is probably a good idea, but I wonder whether lowering 
osd_recovery_max_active and osd_recovery_max_single_start will cause small 
objects to recover unacceptably slowly.

Thoughts?
-Sam
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