Re: Crash of almost full ceph

[Vladimir Bashkirtsev <vladimir@bashkirtsev.com>]

On 07/08/12 01:55, Gregory Farnum wrote:
> There is not yet any such feature, no — dealing with full systems is 
> notoriously hard and we haven't come up with a great solution yet. One 
> thing you can do is experiment with the "mon_osd_min_in_ratio" 
> parameter, which prevents the monitors from marking out more than a 
> certain percentage of the OSD cluster (and without something being 
> marked out, no data will be moved around). If you don't want the 
> cluster to automatically mark any OSDs out, you can also set the 
> "mon_osd_down_out_interval" to zero. -Greg 
But it is good idea to have such feature as fail safe device. Settings 
you speak about may help a bit when cluster is almost full and there 
good number of OSDs but hard refusal of ceph to run recovery if ANY live 
OSD is over certain limit is quite unambiguous. If recovery fails due to 
one OSD is at capacity then it should be handed over to admin to decide 
what to do: rebalance CRUSH, add new OSD, remove some objects. Certainly 
ceph should not be able to fill up OSD with activity which is not 
required (but desired) by end clients.
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