On Mon, Jun 27, 2022 at 8:52 PM Frank Schilder <[email protected]> wrote:
> I think this is just how ceph is. Maybe you should post the output of
> "ceph status", "ceph osd pool stats" and "ceph df" so that we can get an
> idea whether what you look at is expected or not. As I wrote before, object
> recovery is throttled and the recovery bandwidth depends heavily on object
> size. The interesting question is, how many objects per second are
> recovered/rebalanced
>
data:
pools: 11 pools, 369 pgs
objects: 2.45M objects, 9.2 TiB
usage: 20 TiB used, 60 TiB / 80 TiB avail
pgs: 512136/9729081 objects misplaced (5.264%)
343 active+clean
22 active+remapped+backfilling
io:
client: 2.0 MiB/s rd, 344 KiB/s wr, 142 op/s rd, 69 op/s wr
recovery: 34 MiB/s, 8 objects/s
Pool 12 is the only one with any stats.
pool EC-22-Pool id 12
510048/9545052 objects misplaced (5.344%)
recovery io 36 MiB/s, 9 objects/s
client io 1.8 MiB/s rd, 404 KiB/s wr, 86 op/s rd, 72 op/s wr
--- RAW STORAGE ---
CLASS SIZE AVAIL USED RAW USED %RAW USED
hdd 80 TiB 60 TiB 20 TiB 20 TiB 25.45
TOTAL 80 TiB 60 TiB 20 TiB 20 TiB 25.45
--- POOLS ---
POOL ID PGS STORED OBJECTS USED %USED MAX
AVAIL
.mgr 1 1 152 MiB 38 457 MiB 0
9.2 TiB
21BadPool 3 32 8 KiB 1 12 KiB 0
18 TiB
.rgw.root 4 32 1.3 KiB 4 48 KiB 0
9.2 TiB
default.rgw.log 5 32 3.6 KiB 209 408 KiB 0
9.2 TiB
default.rgw.control 6 32 0 B 8 0 B 0
9.2 TiB
default.rgw.meta 7 8 6.7 KiB 20 203 KiB 0
9.2 TiB
rbd_rep_pool 8 32 2.0 MiB 5 5.9 MiB 0
9.2 TiB
default.rgw.buckets.index 9 8 2.0 MiB 33 5.9 MiB 0
9.2 TiB
default.rgw.buckets.non-ec 10 32 1.4 KiB 0 4.3 KiB 0
9.2 TiB
default.rgw.buckets.data 11 32 232 GiB 61.02k 697 GiB 2.41
9.2 TiB
EC-22-Pool 12 128 9.8 TiB 2.39M 20 TiB 41.55
14 TiB
> Maybe provide the output of the first two commands for
> osd_recovery_sleep_hdd=0.05 and osd_recovery_sleep_hdd=0.1 each (wait a bit
> after setting these and then collect the output). Include the applied
> values for osd_max_backfills* and osd_recovery_max_active* for one of the
> OSDs in the pool (ceph config show osd.ID | grep -e osd_max_backfills -e
> osd_recovery_max_active).
>
I didn't notice any speed difference with sleep values changed, but I'll
grab the stats between changes when I have a chance.
ceph config show osd.19 | egrep 'osd_max_backfills|osd_recovery_max_active'
osd_max_backfills 1000
override mon[5]
osd_recovery_max_active 1000
override
osd_recovery_max_active_hdd 1000
override mon[5]
osd_recovery_max_active_ssd 1000
override
>
> I don't really know if on such a small cluster one can expect more than
> what you see. It has nothing to do with network speed if you have a 10G
> line. However, recovery is something completely different from a full
> link-speed copy.
>
> I can tell you that boatloads of tiny objects are a huge pain for
> recovery, even on SSD. Ceph doesn't raid up sections of disks against each
> other, but object for object. This might be a feature request: that PG
> space allocation and recovery should follow the model of LVM extends
> (ideally match with LVM extends) to allow recovery/rebalancing larger
> chunks of storage in one go, containing parts of a large or many small
> objects.
>
> Best regards,
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: Curt <[email protected]>
> Sent: 27 June 2022 17:35:19
> To: Frank Schilder
> Cc: [email protected]
> Subject: Re: [ceph-users] Re: Ceph recovery network speed
>
> Hello,
>
> I had already increased/changed those variables previously. I increased
> the pg_num to 128. Which increased the number of PG's backfilling, but
> speed is still only at 30 MiB/s avg and has been backfilling 23 pg for the
> last several hours. Should I increase it higher than 128?
>
> I'm still trying to figure out if this is just how ceph is or if there is
> a bottleneck somewhere. Like if I sftp a 10G file between servers it's
> done in a couple min or less. Am I thinking of this wrong?
>
> Thanks,
> Curt
>
> On Mon, Jun 27, 2022 at 12:33 PM Frank Schilder <[email protected]<mailto:
> [email protected]>> wrote:
> Hi Curt,
>
> as far as I understood, a 2+2 EC pool is recovering, which makes 1 OSD per
> host busy. My experience is, that the algorithm for selecting PGs to
> backfill/recover is not very smart. It could simply be that it doesn't find
> more PGs without violating some of these settings:
>
> osd_max_backfills
> osd_recovery_max_active
>
> I have never observed the second parameter to change anything (try any
> ways). However, the first one has a large impact. You could try increasing
> this slowly until recovery moves faster. Another parameter you might want
> to try is
>
> osd_recovery_sleep_[hdd|ssd]
>
> Be careful as this will impact client IO. I could reduce the sleep for my
> HDDs to 0.05. With your workload pattern, this might be something you can
> tune as well.
>
> Having said that, I think you should increase your PG count on the EC pool
> as soon as the cluster is healthy. You have only about 20 PGs per OSD and
> large PGs will take unnecessarily long to recover. A higher PG count will
> also make it easier for the scheduler to find PGs for recovery/backfill.
> Aim for a number between 100 and 200. Give the pool(s) with most data
> (#objects) the most PGs.
>
> Best regards,
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: Curt <[email protected]<mailto:[email protected]>>
> Sent: 24 June 2022 19:04
> To: Anthony D'Atri; [email protected]<mailto:[email protected]>
> Subject: [ceph-users] Re: Ceph recovery network speed
>
> 2 PG's shouldn't take hours to backfill in my opinion. Just 2TB enterprise
> HD's.
>
> Take this log entry below, 72 minutes and still backfilling undersized?
> Should it be that slow?
>
> pg 12.15 is stuck undersized for 72m, current state
> active+undersized+degraded+remapped+backfilling, last acting
> [34,10,29,NONE]
>
> Thanks,
> Curt
>
>
> On Fri, Jun 24, 2022 at 8:53 PM Anthony D'Atri <[email protected]
> <mailto:[email protected]>>
> wrote:
>
> > Your recovery is slow *because* there are only 2 PGs backfilling.
> >
> > What kind of OSD media are you using?
> >
> > > On Jun 24, 2022, at 09:46, Curt <[email protected]<mailto:
> [email protected]>> wrote:
> > >
> > > Hello,
> > >
> > > I'm trying to understand why my recovery is so slow with only 2 pg
> > > backfilling. I'm only getting speeds of 3-4/MiB/s on a 10G network. I
> > > have tested the speed between machines with a few tools and all confirm
> > 10G
> > > speed. I've tried changing various settings of priority and recovery
> > sleep
> > > hdd, but still the same. Is this a configuration issue or something
> else?
> > >
> > > It's just a small cluster right now with 4 hosts, 11 osd's per. Please
> > let
> > > me know if you need more information.
> > >
> > > Thanks,
> > > Curt
> > > _______________________________________________
> > > ceph-users mailing list -- [email protected]<mailto:
> [email protected]>
> > > To unsubscribe send an email to [email protected]<mailto:
> [email protected]>
> >
> >
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