Well I decided to try the increase in PGs to 4096 and that seems to have caused some issues:
2018-02-16 12:38:35.798911 mon.carf-ceph-osd01 [ERR] overall HEALTH_ERR 61802168/241154376 objects misplaced (25.628%); Reduced data availability: 2081 pgs inactive, 322 pgs peering; Degraded data redundancy: 552/241154376 objects degraded (0.000%), 3099 pgs unclean, 38 pgs degraded; 163 stuck requests are blocked > 4096 sec
The cluster is actively backfilling misplaced objects, but not all PGs are active at this point and may are stuck peering, stuck unclean, or have a state of unknown:
PG_AVAILABILITY Reduced data availability: 2081 pgs inactive, 322 pgs peering
pg 14.fae is stuck inactive for 253360.025730, current state activating+remapped, last acting [85,12,41]
pg 14.faf is stuck inactive for 253368.511573, current state unknown, last acting []
pg 14.fb0 is stuck peering since forever, current state peering, last acting [94,30,38]
pg 14.fb1 is stuck inactive for 253362.605886, current state activating+remapped, last acting [6,74,34]
[snip]
The health also shows a large number of degraded data redundancy PGs:
PG_DEGRADED Degraded data redundancy: 552/241154376 objects degraded (0.000%), 3099 pgs unclean, 38 pgs degraded
pg 14.fc7 is stuck unclean for 253368.511573, current state unknown, last acting []
pg 14.fc8 is stuck unclean for 531622.531271, current state active+remapped+backfill_wait, last acting [73,132,71]
pg 14.fca is stuck unclean for 420540.396199, current state active+remapped+backfill_wait, last acting [0,80,61]
pg 14.fcb is stuck unclean for 531622.421855, current state activating+remapped, last acting [70,26,75]
[snip]
We also now have a number of stuck requests:
REQUEST_STUCK 163 stuck requests are blocked > 4096 sec
69 ops are blocked > 268435 sec
66 ops are blocked > 134218 sec
28 ops are blocked > 67108.9 sec
osds 7,39,60,103,133 have stuck requests > 67108.9 sec
osds 5,12,13,28,33,40,55,56,61,64,69,70,75,83,92,96,110,114,119,122,123,129,131 have stuck requests > 134218 sec
osds 4,8,10,15,16,20,27,29,30,31,34,37,38,42,43,44,47,48,49,51,52,57,66,68,73,81,84,85,87,90,95,97,99,100,102,105,106,107,108,111,112,113,121,124,127,130,132 have stuck requests > 268435 sec
I tried looking through the mailing list archive on how to solve the stuck requests, and it seems that restarting the OSDs is the right way?
At this point we have just been watching the backfills running and see a steady but slow decrease of misplaced objects. When the cluster is idle, the overall OSD disk utilization is not too bad at roughly 40% on the physical disks running these backfills.
However we still have our backups trying to push new images to the cluster. This worked ok for the first few days, but yesterday we were getting failure alerts. I checked the status of the RGW service and noticed that 2 of the 3 RGW civetweb servers where not responsive. I restarted the RGWs on the ones that appeared hung and that got them working for a while, but then the same condition happened. The RGWs seem to have recovered on their own now, but again the cluster is idle and only backfills are currently doing anything (that I can tell). I did see these log entries:
2018-02-15 16:46:07.541542 7fffe6c56700 1 heartbeat_map is_healthy 'RGWAsyncRadosProcessor::m_tp thread 0x7fffcec26700' had timed out after 600
2018-02-15 16:46:12.541613 7fffe6c56700 1 heartbeat_map is_healthy 'RGWAsyncRadosProcessor::m_tp thread 0x7fffdbc40700' had timed out after 600
2018-02-15 16:46:12.541629 7fffe6c56700 1 heartbeat_map is_healthy 'RGWAsyncRadosProcessor::m_tp thread 0x7fffcec26700' had timed out after 600
2018-02-15 16:46:17.541701 7fffe6c56700 1 heartbeat_map is_healthy 'RGWAsyncRadosProcessor::m_tp thread 0x7fffdbc40700' had timed out after 600
At this point we do not know to proceed with recovery efforts. I tried looking at the ceph docs and mail list archives but wasn’t able to determine the right path forward here.
Any help is appreciated,
-Bryan
From: Bryan Stillwell [mailto:bstillwell@xxxxxxxxxxx]
Sent: Tuesday, February 13, 2018 2:27 PM
To: Bryan Banister <bbanister@xxxxxxxxxxxxxxx>; Janne Johansson <icepic.dz@xxxxxxxxx>
Cc: Ceph Users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: Help rebalancing OSD usage, Luminus 1.2.2
Note: External Email
It may work fine, but I would suggest limiting the number of operations going on at the same time.
Bryan
From: Bryan Banister <bbanister@xxxxxxxxxxxxxxx>
Date: Tuesday, February 13, 2018 at 1:16 PM
To: Bryan Stillwell <bstillwell@xxxxxxxxxxx>, Janne Johansson <icepic.dz@xxxxxxxxx>
Cc: Ceph Users <ceph-users@xxxxxxxxxxxxxx>
Subject: RE: Help rebalancing OSD usage, Luminus 1.2.2
Would it be good to go ahead and do the increase up to 4096 PGs for thee pool given that it's only at 52% done with the rebalance backfilling operations?
Thanks in advance!!
-Bryan
-----Original Message-----
From: Bryan Stillwell [mailto:bstillwell@xxxxxxxxxxx]
Sent: Tuesday, February 13, 2018 12:43 PM
To: Bryan Banister <bbanister@xxxxxxxxxxxxxxx>; Janne Johansson <icepic.dz@xxxxxxxxx>
Cc: Ceph Users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: Help rebalancing OSD usage, Luminus 1.2.2
Note: External Email
-------------------------------------------------
Bryan,
Based off the information you've provided so far, I would say that your largest pool still doesn't have enough PGs.
If you originally had only 512 PGs for you largest pool (I'm guessing .rgw.buckets has 99% of your data), then on a balanced cluster you would have just ~11.5 PGs per OSD (3*512/133). That's way lower than the recommended 100 PGs/OSD.
Based on the number of disks and assuming your .rgw.buckets pool has 99% of the data, you should have around 4,096 PGs for that pool. You'll still end up with an uneven distribution, but the outliers shouldn't be as far out.
Sage recently wrote a new balancer plugin that makes balancing a cluster something that happens automatically. He gave a great talk at LinuxConf Australia that you should check out, here's a link into the video where he talks about the balancer and the need for it:
Even though your objects are fairly large, they are getting broken up into chunks that are spread across the cluster. You can see how large each of your PGs are with a command like this:
ceph pg dump | grep '[0-9]*\.[0-9a-f]*' | awk '{ print $1 "\t" $7 }' |sort -n -k2
You'll see that within a pool the PG sizes are fairly close to the same size, but in your cluster the PGs are fairly large (~200GB would be my guess).
Bryan
From: ceph-users <ceph-users-bounces@xxxxxxxxxxxxxx> on behalf of Bryan Banister <bbanister@xxxxxxxxxxxxxxx>
Date: Monday, February 12, 2018 at 2:19 PM
To: Janne Johansson <icepic.dz@xxxxxxxxx>
Cc: Ceph Users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: Help rebalancing OSD usage, Luminus 1.2.2
Hi Janne and others,
We used the “ceph osd reweight-by-utilization “ command to move a small amount of data off of the top four OSDs by utilization. Then we updated the pg_num and pgp_num on the pool from 512 to 1024 which started moving roughly 50% of the objects around as a result. The unfortunate issue is that the weights on the OSDs are still roughly equivalent and the OSDs that are nearfull were still getting allocated objects during the rebalance backfill operations.
At this point I have made some massive changes to the weights of the OSDs in an attempt to stop Ceph from allocating any more data to OSDs that are getting close to full. Basically the OSD with the lowest utilization remains weighted at 1 and the rest of the OSDs are now reduced in weight based on the percent usage of the OSD + the %usage of the OSD with the amount of data (21% at the time). This means the OSD that is at the most full at this time at 86% full now has a weight of only .33 (it was at 89% when reweight was applied). I’m not sure this is a good idea, but it seemed like the only option I had. Please let me know if I’m making a bad situation worse!
I still have the question on how this happened in the first place and how to prevent it from happening going forward without a lot of monitoring and reweighting on weekends/etc to keep things balanced. It sounds like Ceph is really expecting that objects stored into a pool will roughly have the same size, is that right?
Our backups going into this pool have very large variation in size, so would it be better to create multiple pools based on expected size of objects and then put backups of similar size into each pool?
The backups also have basically the same names with the only difference being the date which it was taken (e.g. backup name difference in subsequent days can be one digit at times), so does this mean that large backups with basically the same name will end up being placed in the same PGs based on the CRUSH calculation using the object name?
Thanks,
-Bryan
From: Janne Johansson [mailto:icepic.dz@xxxxxxxxx]
Sent: Wednesday, January 31, 2018 9:34 AM
To: Bryan Banister <bbanister@xxxxxxxxxxxxxxx>
Cc: Ceph Users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: Help rebalancing OSD usage, Luminus 1.2.2
Note: External Email
2018-01-31 15:58 GMT+01:00 Bryan Banister <mailto:bbanister@xxxxxxxxxxxxxxx>:
Given that this will move data around (I think), should we increase the pg_num and pgp_num first and then see how it looks?
I guess adding pgs and pgps will move stuff around too, but if the PGCALC formula says you should have more then that would still be a good
start. Still, a few manual reweights first to take the 85-90% ones down might be good, some move operations are going to refuse adding things
to too-full OSDs, so you would not want to get accidentally bumped above such a limit due to some temp-data being created during moves.
Also, dont bump pgs like crazy, you can never move down. Aim for getting ~100 per OSD at most, and perhaps even then in smaller steps so
that the creation (and evening out of data to the new empty PGs) doesn't kill normal client I/O perf in the meantime.
--
May the most significant bit of your life be positive.
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