Re: Adding OSD's results in slow ops, inactive PG's

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I'm glad to hear (or read) that it worked for you as well. :-)

Zitat von Torkil Svensgaard <torkil@xxxxxxxx>:

On 18/01/2024 09:30, Eugen Block wrote:
Hi,

[ceph: root@lazy /]# ceph-conf --show-config | egrep osd_max_pg_per_osd_hard_ratio
osd_max_pg_per_osd_hard_ratio = 3.000000

I don't think this is the right tool, it says:

--show-config-value <key>       Print the corresponding ceph.conf value
                                that matches the specified key. Also searches
                                global defaults.

I suggest to query the daemon directly:

storage01:~ # ceph config set osd osd_max_pg_per_osd_hard_ratio 5

storage01:~ # ceph tell osd.0 config get osd_max_pg_per_osd_hard_ratio
{
    "osd_max_pg_per_osd_hard_ratio": "5.000000"
}

Copy that, verified to be 5 now.

Daemons are running but those last OSDs won't come online.
I've tried upping bdev_aio_max_queue_depth but it didn't seem to make a difference.

I don't have any good idea for that right now except what you already tried. Which values for bdev_aio_max_queue_depth have you tried?

The previous value was 1024, I bumped it to 4096.

A couple of the OSDs seemingly stuck on the aio thing has now come to, so I went ahead and added the rest. Some of them came in right away, some are stuck on the aio thing. Hopefully they will recover eventually.

Thanks you again for the osd_max_pg_per_osd_hard_ratio suggestion, that seems to have solved the core issue =)

Mvh.

Torkil


Zitat von Torkil Svensgaard <torkil@xxxxxxxx>:

On 18/01/2024 07:48, Eugen Block wrote:
Hi,

 -3281> 2024-01-17T14:57:54.611+0000 7f2c6f7ef540  0 osd.431 2154828 load_pgs opened 750 pgs <---

I'd say that's close enough to what I suspected. ;-) Not sure why the "maybe_wait_for_max_pg" message isn't there but I'd give it a try with a higher osd_max_pg_per_osd_hard_ratio.

Might have helped, not quite sure.

I've set these since I wasn't sure which one was the right one?:

"
ceph config dump | grep osd_max_pg_per_osd_hard_ratio
global            advanced  osd_max_pg_per_osd_hard_ratio    5.000000 osd               advanced  osd_max_pg_per_osd_hard_ratio    5.000000
"

Restarted MONs and MGRs. Still getting this with ceph-conf though:

"
[ceph: root@lazy /]# ceph-conf --show-config | egrep osd_max_pg_per_osd_hard_ratio
osd_max_pg_per_osd_hard_ratio = 3.000000
"

I re-added a couple small SSD OSDs and they came in just fine. I then added a couple HDD OSDs and they also came in after a bit of aio_submit spam. I added a couple more and have now been looking at this for 40 minutes:


"
...

2024-01-18T07:42:01.789+0000 7f734fa04700 -1 bdev(0x56295d586400 /var/lib/ceph/osd/ceph-436/block) aio_submit retries 10 2024-01-18T07:42:01.808+0000 7f734fa04700 -1 bdev(0x56295d586400 /var/lib/ceph/osd/ceph-436/block) aio_submit retries 4 2024-01-18T07:42:01.819+0000 7f735d1b8700 -1 bdev(0x56295d586400 /var/lib/ceph/osd/ceph-436/block) aio_submit retries 82 2024-01-18T07:42:07.499+0000 7f734fa04700 -1 bdev(0x56295d586400 /var/lib/ceph/osd/ceph-436/block) aio_submit retries 6 2024-01-18T07:42:07.542+0000 7f734fa04700 -1 bdev(0x56295d586400 /var/lib/ceph/osd/ceph-436/block) aio_submit retries 8 2024-01-18T07:42:07.554+0000 7f735d1b8700 -1 bdev(0x56295d586400 /var/lib/ceph/osd/ceph-436/block) aio_submit retries 108
...
"

Daemons are running but those last OSDs won't come online.

I've tried upping bdev_aio_max_queue_depth but it didn't seem to make a difference.

Mvh.

Torkil


Zitat von Torkil Svensgaard <torkil@xxxxxxxx>:

On 17-01-2024 22:20, Eugen Block wrote:
Hi,

Hi

this sounds a bit like a customer issue we had almost two years ago. Basically, it was about mon_max_pg_per_osd (default 250) which was exceeded during the first activating OSD (and the last remaining stopping OSD). You can read all the details in the lengthy thread [1]. But if this is was the actual issue you probably should see something like this in the logs:

2022-04-06 14:24:55.256 7f8bb5a0e700 1 osd.8 43377 maybe_wait_for_max_pg withhold creation of pg 75.56s16: 750 >= 750

In our case we did the opposite and removed an entire host. I'll just quote Josh's explanation from the mentioned thread:

1. All OSDs on the host are purged per above.
2. New OSDs are created.
3. As they come up, one by one, CRUSH starts to assign PGs to them.
Importantly, when the first OSD comes up, it gets a large number of
OSDs, exceeding mon_max_pg_per_osd. Thus, some of these PGs don't
activate.
4. As each of the remaining OSDs come up, CRUSH re-assigns some PGs to them.
5. Finally, all OSDs are up. However, any PGs that were stuck in
"activating" from step 3 that were _not_ reassigned to other OSDs are
still stuck in "activating", and need a repeer or OSD down/up cycle to
restart peering for them. (At least in Pacific, tweaking
mon_max_pg_per_osd also allows some of these PGs to make peering
progress.)

Note that during backfill/recovery the limit is 750 (mon_max_pg_per_osd * osd_max_pg_per_osd_hard_ratio ==> 250 * 3 = 750). As a workaround we increased osd_max_pg_per_osd_hard_ratio to 5 and the issue was never seen again.
Can you check the logs for that message?

I can't find that error in the logs but I notice this:

"
[root@dreamy 8ee2d228-ed21-4580-8bbf-0649f229e21d]# less ceph-osd.431.log | grep load_pgs
2024-01-17T13:07:41.202+0000 7f74eae5f540  0 osd.431 0 load_pgs
2024-01-17T13:07:41.202+0000 7f74eae5f540  0 osd.431 0 load_pgs opened 0 pgs
2024-01-17T13:48:31.781+0000 7f381e34b540  0 osd.431 2154180 load_pgs
2024-01-17T13:48:37.881+0000 7f381e34b540  0 osd.431 2154180 load_pgs opened 559 pgs
2024-01-17T13:52:54.473+0000 7f5e713a7540  0 osd.431 2154420 load_pgs
2024-01-17T13:53:00.156+0000 7f5e713a7540  0 osd.431 2154420 load_pgs opened 559 pgs
2024-01-17T13:58:42.052+0000 7f23c3482540  0 osd.431 2154580 load_pgs
2024-01-17T13:58:47.710+0000 7f23c3482540  0 osd.431 2154580 load_pgs opened 559 pgs  -5202> 2024-01-17T13:58:42.052+0000 7f23c3482540  0 osd.431 2154580 load_pgs  -5184> 2024-01-17T13:58:47.710+0000 7f23c3482540  0 osd.431 2154580 load_pgs opened 559 pgs
2024-01-17T14:57:46.714+0000 7f2c6f7ef540  0 osd.431 2154828 load_pgs
2024-01-17T14:57:54.611+0000 7f2c6f7ef540  0 osd.431 2154828 load_pgs opened 750 pgs  -3363> 2024-01-17T14:57:46.714+0000 7f2c6f7ef540  0 osd.431 2154828 load_pgs  -3281> 2024-01-17T14:57:54.611+0000 7f2c6f7ef540  0 osd.431 2154828 load_pgs opened 750 pgs <---
"

We'll try increasing osd_max_pg_per_osd_hard_ratio to 5 tomorrow when onsite just to check if it makes a difference.

This is what we have in the log for osd.11, one of the stalled osds, when osd.431 was started:

"
2024-01-17T14:57:59.064+0000 7f644154e700  0 log_channel(cluster) log [INF] : 11.857s0 continuing backfill to osd.104(4) from (2151654'3111903,2154845'3112716] MIN to 2154845'3112716 2024-01-17T14:57:59.064+0000 7f644154e700  0 log_channel(cluster) log [DBG] : 11.857s0 starting backfill to osd.128(3) from (2151654'3111903,2154278'3112714] MIN to 2154845'3112716 2024-01-17T14:57:59.067+0000 7f643fd4b700  0 log_channel(cluster) log [DBG] : 11.5e4s0 starting backfill to osd.431(5) from (2151000'3067292,2154631'3068041] MIN to 2154848'3068052 2024-01-17T14:57:59.067+0000 7f644054c700  0 log_channel(cluster) log [INF] : 11.cc8s0 continuing backfill to osd.184(5) from (2151675'2997168,2154838'2997942] MIN to 2154838'2997942 2024-01-17T14:57:59.067+0000 7f644054c700  0 log_channel(cluster) log [DBG] : 11.cc8s0 starting backfill to osd.431(1) from (2151675'2997168,2154820'2997923] MIN to 2154838'2997942 2024-01-17T14:57:59.071+0000 7f643f54a700  0 log_channel(cluster) log [DBG] : 11.883s0 starting backfill to osd.431(4) from (2151058'2837151,2154693'2837901] MIN to 2154845'2837919 2024-01-17T14:57:59.079+0000 7f6440d4d700  0 log_channel(cluster) log [DBG] : 11.637s0 starting backfill to osd.431(5) from (2151654'3204863,2154801'3205673] MIN to 2154845'3205687 2024-01-17T14:57:59.106+0000 7f643fd4b700  0 log_channel(cluster) log [INF] : 11.4f9s0 continuing backfill to osd.149(3) from (2151654'3169077,2154845'3169891] MIN to 2154845'3169891 2024-01-17T14:57:59.106+0000 7f643fd4b700  0 log_channel(cluster) log [DBG] : 11.4f9s0 starting backfill to osd.431(4) from (2151654'3169077,2154183'3169887] MIN to 2154845'3169891 2024-01-17T14:57:59.122+0000 7f644054c700  0 log_channel(cluster) log [DBG] : 11.c73s0 starting backfill to osd.431(3) from (2152025'3130484,2154822'3131249] MIN to 2154845'3131256 2024-01-17T14:57:59.135+0000 7f644154e700  0 log_channel(cluster) log [INF] : 11.857s0 continuing backfill to osd.272(0) from (2151654'3111903,2154845'3112716] MIN to 2154845'3112716 2024-01-17T14:57:59.136+0000 7f644154e700  0 log_channel(cluster) log [INF] : 11.857s0 continuing backfill to osd.333(2) from (2151654'3111903,2154845'3112716] MIN to 2154845'3112716 2024-01-17T14:57:59.136+0000 7f644154e700  0 log_channel(cluster) log [INF] : 11.857s0 continuing backfill to osd.423(5) from (2151654'3111903,2154845'3112716] MIN to 2154845'3112716 2024-01-17T14:57:59.136+0000 7f644154e700  0 log_channel(cluster) log [DBG] : 11.857s0 starting backfill to osd.431(1) from (2151654'3111903,2154278'3112714] MIN to 2154845'3112716 2024-01-17T14:57:59.161+0000 7f644154e700  0 log_channel(cluster) log [INF] : 11.f8cs0 continuing backfill to osd.105(4) from (2152025'3065404,2154848'3066167] MIN to 2154848'3066167 2024-01-17T14:57:59.162+0000 7f644154e700  0 log_channel(cluster) log [INF] : 11.f8cs0 continuing backfill to osd.421(2) from (2152025'3065404,2154848'3066167] MIN to 2154848'3066167 2024-01-17T14:57:59.162+0000 7f644154e700  0 log_channel(cluster) log [DBG] : 11.f8cs0 starting backfill to osd.431(5) from (0'0,0'0] MAX to 2154848'3066167 2024-01-17T14:57:59.167+0000 7f643f54a700  0 log_channel(cluster) log [DBG] : 37.6ees0 starting backfill to osd.431(8) from (0'0,0'0] MAX to 2154128'24444 2024-01-17T14:58:33.532+0000 7f6455d77700 -1 osd.11 2154852 get_health_metrics reporting 1 slow ops, oldest is osd_op(client.1823267746.0:788334371 11.f8cs0 11.2dd6f8c (undecoded) ondisk+
write+known_if_redirected e2154852)
...
"

Not sure if that provides any clues.

Thanks!

Mvh.

Torkil

Regards,
Eugen

[1] https://www.spinics.net/lists/ceph-users/msg71933.html

Zitat von Ruben Vestergaard <rubenv@xxxxxxxx>:

Hi

We have a cluster with which currently looks like so:

    services:
      mon: 5 daemons, quorum lazy,jolly,happy,dopey,sleepy (age 13d)
      mgr: jolly.tpgixt(active, since 25h), standbys: dopey.lxajvk, lazy.xuhetq
      mds: 1/1 daemons up, 2 standby
      osd: 449 osds: 425 up (since 15m), 425 in (since 5m); 5104 remapped pgs
        data:
      volumes: 1/1 healthy
      pools:   13 pools, 11153 pgs
      objects: 304.11M objects, 988 TiB
      usage:   1.6 PiB used, 1.4 PiB / 2.9 PiB avail
      pgs:     6/1617270006 objects degraded (0.000%)
               366696947/1617270006 objects misplaced (22.674%)
               6043 active+clean
               5041 active+remapped+backfill_wait
               66   active+remapped+backfilling
               2    active+recovery_wait+degraded+remapped
               1    active+recovering+degraded


It's currently rebalancing after adding a node, but this rebalance has been rather slow -- right now it's running 66 backfills, but it seems to stabilize around 8 backfills eventually. We figured that perhaps adding another node might speed things up.

Immediately upon adding the node, we get slow ops and inactive PG's. Removing the new node gets us back in working order.

It turns out that even adding 1 OSD breaks the cluster, and immediately sends it here:

    [WRN] PG_DEGRADED: Degraded data redundancy: 6/1617265712 objects degraded (0.000%), 3 pgs degraded         pg 37.c8 is active+recovery_wait+degraded+remapped, acting [410,163,236,209,7,283,155,143,78]         pg 37.1a1 is active+recovering+degraded, acting [234,424,163,74,22,128,177,153,181]         pg 37.1da is active+recovery_wait+degraded+remapped, acting [163,408,230,190,93,284,50,78,44]     [WRN] SLOW_OPS: 22 slow ops, oldest one blocked for 54 sec, daemons [osd.11,osd.110,osd.112,osd.117,osd.120,osd.123,osd.13,osd. 136,osd.144,osd.157]... have slow ops.

The OSD added had number 431, so it does not appear to be the immediate cause of the slow ops, however, removing 431 immediately clears the problem.

We thought we might be experiencing 'Crush giving up too soon' symptoms [1], as we have seen similar behaviour on another pool, but it does not appear to be the case here. We went through the motions described on the page and everything looked OK.

At least one pool which stops working is a 4+2 EC pool, placed on spinning rust, some 200-ish disks distributed across 13 nodes. I'm not sure if other pools break, but that particular 4+2 EC pool is rather important so I'm a little wary of experimenting blindly.

Any thoughts on where to look next?

Thanks,
Ruben Vestergaard

[1] https://docs.ceph.com/en/reef/rados/troubleshooting/ troubleshooting-pg/#crush-gives-up-too-soon
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--
Torkil Svensgaard
Systems Administrator
Danish Research Centre for Magnetic Resonance DRCMR, Section 714
Copenhagen University Hospital Amager and Hvidovre
Kettegaard Allé 30, 2650 Hvidovre, Denmark
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To unsubscribe send an email to ceph-users-leave@xxxxxxx


_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx

--
Torkil Svensgaard
Sysadmin
MR-Forskningssektionen, afs. 714
DRCMR, Danish Research Centre for Magnetic Resonance
Hvidovre Hospital
Kettegård Allé 30
DK-2650 Hvidovre
Denmark
Tel: +45 386 22828
E-mail: torkil@xxxxxxxx
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx


_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx

--
Torkil Svensgaard
Sysadmin
MR-Forskningssektionen, afs. 714
DRCMR, Danish Research Centre for Magnetic Resonance
Hvidovre Hospital
Kettegård Allé 30
DK-2650 Hvidovre
Denmark
Tel: +45 386 22828
E-mail: torkil@xxxxxxxx
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx


_______________________________________________
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To unsubscribe send an email to ceph-users-leave@xxxxxxx




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