Hi Florian,
thank you for your answer.
We have already set the IO scheduler to cfq in order to be able to lower the priority of the scrub operations.
My problem is that I've found different values set for the same parameter, and in each case they were doing it in order to achieve the same thing as we do.
This is why I was asking for some more details about this parameter. Is the value 0 or 7 which will set the scrub to the lowest priority? I want my ceph cluster to be responsive for the client requests, and do the scrub in the background.
I'm open to any ideas/suggestions which would help to improove the cluster's responsiveness during deep scrub operations.
Kind regards,
Laszlo
On 12.03.2017 21:21, Florian Haas wrote:
On Sat, Mar 11, 2017 at 4:24 PM, Laszlo Budai <laszlo@xxxxxxxxxxxxxxxx> wrote:
Can someone explain the meaning of osd_disk_thread_ioprio_priority. I'm
[...]
Now I am confused .... :(
Can somebody bring some light here?
Only to confuse you some more. If you are running Jewel or above then
scrubbing is now done in the main operation thread and so setting this
value
will have no effect.
There is the hammer version of ceph.
As the documentation
(http://docs.ceph.com/docs/hammer/rados/configuration/osd-config-ref/)
explains, osd_disk_thread_ioprio_priority is ineffective unless you're
using the CFQ I/O scheduler. Most server I/O stack configurations
(including typical Ceph OSD nodes) run with the deadline scheduler
either by default or by best-practice configuration, so this option
has no effect on such systems.
You can check /sys/block/<device>/queue/scheduler to see which
scheduler your devices are currently using.
Cheers,
Florian
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