On 1/27/2014 1:45 PM, Sage Weil wrote:
There is also
ceph osd set noscrub
and then later
ceph osd unset noscrub
In my experience scrub isn't nearly as much of a problem as deep-scrub.
On a IOPS constrained cluster with writes approaching the available
aggregate spindle performance minus replication penalty and possibly
co-located osd journal penalty, scrub may run without any disruption.
But deep-scrub tends to make iowait on the spindles get ugly.
To disable/enable deep-scrub use:
ceph osd set nodeep-scrub
ceph osd unset nodeep-scrub
I forget whether this pauses an in-progress PG scrub or just makes it stop
when it gets to the next PG boundary.
sage
On Mon, 27 Jan 2014, Kyle Bader wrote:
Are there any tools we are not aware of for controlling, possibly pausing,
deep-scrub and/or getting some progress about the procedure ?
Also since I believe it would be a bad practice to disable deep-scrubbing do you
have any recommendations of how to work around (or even solve) this issue ?
The periodicity of scrubs is controllable with these tunables:
osd scrub max interval
osd deep scrub interval
You may also be interested in adjusting:
osd scrub load threshold
More information on the docs page:
http://ceph.com/docs/master/rados/configuration/osd-config-ref/#scrubbing
I rarely run into a situation where 1m average of load is <0.5 on a
multi-core server running osds, so deep scrub for me is always triggered
by the 'osd scrub max interval'. I've had a bug out there to take core
count into consideration:
http://tracker.ceph.com/issues/6296
The documentation used to say the "Default is 50%" implying that this
feature should allow scrub to start with a much higher load than 0.5
will allow on multi-core systems. The documentation has changed, but the
default of 0.5 is still artificially suppressing deep-scrub from
opportunistically starting on relatively idle multi-core systems.
That being said, deep-scrub may be better served with an
osd_scrub_iops_threshold mechanism instead of (or in addition to) the
osd_scrub_load_threshold.
- Mike
Hope that helps some!
--
Kyle
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