On Mon, 10 Dec 2018 21:01:31 -0500 Tyler Bishop wrote:
> LVM | dm-0 | busy 101% | read 137 | write 1761 |
> KiB/r 4 | KiB/w 30 | MBr/s 0.1 | MBw/s 5.3 | avq
> 185.42 | avio 5.31 ms |
> DSK | sdb | busy 100% | read 127 | write 1208 |
> KiB/r 4 | KiB/w 32 | MBr/s 0.1 | MBw/s 3.9 | avq
> 58.39 | avio 7.49 ms |
> _____________________________________________
>
OK, after stretching that back out to its original length, you're having
100% busy SSDs at just 5MB/s writes.
hitting "1" in atop will give you per second results like this for an
Intel DC S3600 in a cache tier (filestore):
----
DSK | sde | | busy 3% | | read
0/s | | write 476/s | | KiB/r 0 |
| | KiB/w 17 | | MBr/s 0.00 |
| MBw/s 8.34 | | avq 49.35 | | avio 0.06 ms |
---
If these SSDs worked decently with filestore I can't really see how they
would be this much worse with bluestore, still got an original setup to
compare?
Anything else like controller cache/battery/BIOS settings/etc that might
have changed during the migration?
Christian
> Tyler Bishop
> EST 2007
>
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> On Mon, Dec 10, 2018 at 8:57 PM Christian Balzer <ch...@gol.com> wrote:
> >
> > Hello,
> >
> > On Mon, 10 Dec 2018 20:43:40 -0500 Tyler Bishop wrote:
> >
> > > I don't think thats my issue here because I don't see any IO to justify
> > > the
> > > latency. Unless the IO is minimal and its ceph issuing a bunch of
> > > discards
> > > to the ssd and its causing it to slow down while doing that.
> > >
> >
> > What does atop have to say?
> >
> > Discards/Trims are usually visible in it, this is during a fstrim of a
> > RAID1 / :
> > ---
> > DSK | sdb | busy 81% | read 0 | write 8587 | MBw/s
> > 2323.4 | avio 0.47 ms |
> > DSK | sda | busy 70% | read 2 | write 8587 | MBw/s
> > 2323.4 | avio 0.41 ms |
> > ---
> >
> > The numbers tend to be a lot higher than what the actual interface is
> > capable of, clearly the SSD is reporting its internal activity.
> >
> > In any case, it should give a good insight of what is going on activity
> > wise.
> > Also for posterity and curiosity, what kind of SSDs?
> >
> > Christian
> >
> > > Log isn't showing anything useful and I have most debugging disabled.
> > >
> > >
> > >
> > > On Mon, Dec 10, 2018 at 7:43 PM Mark Nelson <mnel...@redhat.com> wrote:
> > >
> > > > Hi Tyler,
> > > >
> > > > I think we had a user a while back that reported they had background
> > > > deletion work going on after upgrading their OSDs from filestore to
> > > > bluestore due to PGs having been moved around. Is it possible that your
> > > > cluster is doing a bunch of work (deletion or otherwise) beyond the
> > > > regular client load? I don't remember how to check for this off the top
> > > > of my head, but it might be something to investigate. If that's what it
> > > > is, we just recently added the ability to throttle background deletes:
> > > >
> > > > https://github.com/ceph/ceph/pull/24749
> > > >
> > > >
> > > > If the logs/admin socket don't tell you anything, you could also try
> > > > using our wallclock profiler to see what the OSD is spending it's time
> > > > doing:
> > > >
> > > > https://github.com/markhpc/gdbpmp/
> > > >
> > > >
> > > > ./gdbpmp -t 1000 -p`pidof ceph-osd` -o foo.gdbpmp
> > > >
> > > > ./gdbpmp -i foo.gdbpmp -t 1
> > > >
> > > >
> > > > Mark
> > > >
> > > > On 12/10/18 6:09 PM, Tyler Bishop wrote:
> > > > > Hi,
> > > > >
> > > > > I have an SSD only cluster that I recently converted from filestore to
> > > > > bluestore and performance has totally tanked. It was fairly decent
> > > > > before, only having a little additional latency than expected. Now
> > > > > since converting to bluestore the latency is extremely high, SECONDS.
> > > > > I am trying to determine if it an issue with the SSD's or Bluestore
> > > > > treating them differently than filestore... potential garbage
> > > > > collection? 24+ hrs ???
> > > > >
> > > > > I am now seeing constant 100% IO utilization on ALL of the devices and
> > > > > performance is terrible!
> > > > >
> > > > > IOSTAT
> > > > >
> > > > > avg-cpu: %user %nice %system %iowait %steal %idle
> > > > > 1.37 0.00 0.34 18.59 0.00 79.70
> > > > >
> > > > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
> > > > > avgrq-sz avgqu-sz await r_await w_await svctm %util
> > > > > sda 0.00 0.00 0.00 9.50 0.00 64.00
> > > > > 13.47 0.01 1.16 0.00 1.16 1.11 1.05
> > > > > sdb 0.00 96.50 4.50 46.50 34.00 11776.00
> > > > > 463.14 132.68 1174.84 782.67 1212.80 19.61 100.00
> > > > > dm-0 0.00 0.00 5.50 128.00 44.00 8162.00
> > > > > 122.94 507.84 1704.93 674.09 1749.23 7.49 100.00
> > > > >
> > > > > avg-cpu: %user %nice %system %iowait %steal %idle
> > > > > 0.85 0.00 0.30 23.37 0.00 75.48
> > > > >
> > > > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
> > > > > avgrq-sz avgqu-sz await r_await w_await svctm %util
> > > > > sda 0.00 0.00 0.00 3.00 0.00 17.00
> > > > > 11.33 0.01 2.17 0.00 2.17 2.17 0.65
> > > > > sdb 0.00 24.50 9.50 40.50 74.00 10000.00
> > > > > 402.96 83.44 2048.67 1086.11 2274.46 20.00 100.00
> > > > > dm-0 0.00 0.00 10.00 33.50 78.00 2120.00
> > > > > 101.06 287.63 8590.47 1530.40 10697.96 22.99 100.00
> > > > >
> > > > > avg-cpu: %user %nice %system %iowait %steal %idle
> > > > > 0.81 0.00 0.30 11.40 0.00 87.48
> > > > >
> > > > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
> > > > > avgrq-sz avgqu-sz await r_await w_await svctm %util
> > > > > sda 0.00 0.00 0.00 6.00 0.00 40.25
> > > > > 13.42 0.01 1.33 0.00 1.33 1.25 0.75
> > > > > sdb 0.00 314.50 15.50 72.00 122.00 17264.00
> > > > > 397.39 61.21 1013.30 740.00 1072.13 11.41 99.85
> > > > > dm-0 0.00 0.00 10.00 427.00 78.00 27728.00
> > > > > 127.26 224.12 712.01 1147.00 701.82 2.28 99.85
> > > > >
> > > > > avg-cpu: %user %nice %system %iowait %steal %idle
> > > > > 1.22 0.00 0.29 4.01 0.00 94.47
> > > > >
> > > > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s
> > > > > avgrq-sz avgqu-sz await r_await w_await svctm %util
> > > > > sda 0.00 0.00 0.00 3.50 0.00 17.00
> > > > > 9.71 0.00 1.29 0.00 1.29 1.14 0.40
> > > > > sdb 0.00 0.00 1.00 39.50 8.00 10112.00
> > > > > 499.75 78.19 1711.83 1294.50 1722.39 24.69 100.00
> > > > >
> > > > >
> > > > > _______________________________________________
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> > > > _______________________________________________
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> > > >
> >
> >
> > --
> > Christian Balzer Network/Systems Engineer
> > ch...@gol.com Rakuten Communications
>
--
Christian Balzer Network/Systems Engineer
ch...@gol.com Rakuten Communications
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