Task #5786
Updated by Nico Schottelius over 5 years ago
h2. Change speed for i/o recovery
By default we want to keep I/O recovery traffic low to not impact customer experience. However when multiple disks fail at the same point, we might want to prioritise recover for data safety over performance.
The default configuration on our servers contains:
<pre>
[osd]
osd max backfills = 1
osd recovery max active = 1
osd recovery op priority = 2
</pre>
The important settings are *osd max backfills* and *osd recovery max active*, the priority is always kept low so that regular I/O has priority.
To adjust the number of backfills *per osd* and to change the *number of threads* used for recovery, we can use on any node with the admin keyring:
<pre>
ceph tell osd.* injectargs '--osd-max-backfills Y'
ceph tell osd.* injectargs '--osd-recovery-max-active X'
</pre>
where Y and X are the values that we want to use. Experience shows that Y=5 and X=5 doubles to triples the recovery performance, whereas X=10 and Y=10 increases performance 5 times.