I tend to set it whenever I don't want to be bothered by storage
performance woes (nights I value sleep, etc).
This cluster is bounded by relentless small writes (it has a couple
dozen rbd volumes backing video surveillance DVRs). Some of the software
we run is completely unaffected whereas other software falls apart
during periods of deep-scrubs. I theorize it has to do with the
individual software's attitude about flushing to disk / buffering.
- Mike
On 5/20/2014 8:31 PM, Aaron Ten Clay wrote:
> For what it's worth, version 0.79 has different headers, and the awk
> command needs $19 instead of $20. But here is the output I have on a
> small cluster that I recently rebuilt:
>
> $ ceph pg dump all | grep active | awk '{ print $19}' | sort -k1 | uniq -c
> dumped all in format plain
> 1 2014-05-15
> 2 2014-05-17
> 19 2014-05-18
> 193 2014-05-19
> 105 2014-05-20
>
> I have set noscrub and nodeep-scrub, as well as noout and nodown off and
> on while I performed various maintenance, but that hasn't (apparently)
> impeded the regular schedule.
>
> With what frequency are you setting the nodeep-scrub flag?
>
> -Aaron
>
>
> On Tue, May 20, 2014 at 5:21 PM, Mike Dawson <mike.dawson at cloudapt.com
> <mailto:mike.dawson at cloudapt.com>> wrote:
>
> Today I noticed that deep-scrub is consistently missing some of my
> Placement Groups, leaving me with the following distribution of PGs
> and the last day they were successfully deep-scrubbed.
>
> # ceph pg dump all | grep active | awk '{ print $20}' | sort -k1 |
> uniq -c
> 5 2013-11-06
> 221 2013-11-20
> 1 2014-02-17
> 25 2014-02-19
> 60 2014-02-20
> 4 2014-03-06
> 3 2014-04-03
> 6 2014-04-04
> 6 2014-04-05
> 13 2014-04-06
> 4 2014-04-08
> 3 2014-04-10
> 2 2014-04-11
> 50 2014-04-12
> 28 2014-04-13
> 14 2014-04-14
> 3 2014-04-15
> 78 2014-04-16
> 44 2014-04-17
> 8 2014-04-18
> 1 2014-04-20
> 16 2014-05-02
> 69 2014-05-04
> 140 2014-05-05
> 569 2014-05-06
> 9231 2014-05-07
> 103 2014-05-08
> 514 2014-05-09
> 1593 2014-05-10
> 393 2014-05-16
> 2563 2014-05-17
> 1283 2014-05-18
> 1640 2014-05-19
> 1979 2014-05-20
>
> I have been running the default "osd deep scrub interval" of once
> per week, but have disabled deep-scrub on several occasions in an
> attempt to avoid the associated degraded cluster performance I have
> written about before.
>
> To get the PGs longest in need of a deep-scrub started, I set the
> nodeep-scrub flag, and wrote a script to manually kick off
> deep-scrub according to age. It is processing as expected.
>
> Do you consider this a feature request or a bug? Perhaps the code
> that schedules PGs to deep-scrub could be improved to prioritize PGs
> that have needed a deep-scrub the longest.
>
> Thanks,
> Mike Dawson
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