Hi list,
I've been searching the mail archive and the web for some help. I
tried the things I found, but I can't see the effects. We use Ceph for
our Openstack environment.
When our cluster (2 pools, each 4092 PGs, in 20 OSDs on 4 nodes, 3
MONs) starts deep-scrubbing, it's impossible to work with the VMs.
Currently, the deep-scrubs happen to start on Monday, which is
unfortunate. I already plan to start the next deep-scrub on Saturday,
so it has no impact on our work days. But if I imagine we had a large
multi-datacenter, such performance breaks are not reasonable. So I'm
wondering how do you guys manage that?
What I've tried so far:
ceph tell osd.* injectargs '--osd_scrub_sleep 0.1'
ceph tell osd.* injectargs '--osd_disk_thread_ioprio_priority 7'
ceph tell osd.* injectargs '--osd_disk_thread_ioprio_class idle'
ceph tell osd.* injectargs '--osd_scrub_begin_hour 0'
ceph tell osd.* injectargs '--osd_scrub_end_hour 7'
And I also added these options to the ceph.conf.
To be able to work again, I had to set the nodeep-scrub option and
unset it when I left the office. Today, I see the cluster
deep-scrubbing again, but only one PG at a time, it seems that now the
default for osd_max_scrubs is working now and I don't see major
impacts yet.
But is there something else I can do to reduce the performance impact?
I just found [1] and will have a look into it.
[1] http://prob6.com/en/ceph-pg-deep-scrub-cron/
Thanks!
Eugen
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