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Sage, Unfortunately the mon election problem came back yesterday and it makes it really hard to get a cluster to stay healthy. A brief unexpected network outage occurred and sent the cluster into a frenzy and when I had it 95% healthy the mons started their nonstop reelections. In the previous logs I sent were you able to identify why the mons are constantly electing? The elections seem to be triggered by the below paxos message but do you know which lease timeout is being reached or why the lease isn't renewed instead of calling for an election? One thing I tried was to shutdown the entire cluster and bring up only the mon and mgr. The mons weren't able to hold their quorum with no osds running and the ceph-mon ms_dispatch thread runs at 100% for > 60s at a time. 2018-09-19 03:56:21.729 7f4344ec1700 1 mon.sephmon2@1(peon).paxos(paxos active c 133382665..133383355) lease_timeout -- calling new election Thanks Kevin On 09/10/2018 07:06 AM, Sage Weil wrote:
I took a look at the mon log you sent. A few things I noticed: - The frequent mon elections seem to get only 2/3 mons about half of the time. - The messages coming in a mostly osd_failure, and half of those seem to be recoveries (cancellation of the failure message). It does smell a bit like a networking issue, or some tunable that relates to the messaging layer. It might be worth looking at an OSD log for an osd that reported a failure and seeing what error code it coming up on the failed ping connection? That might provide a useful hint (e.g., ECONNREFUSED vs EMFILE or something). I'd also confirm that with nodown set the mon quorum stabilizes... sage On Mon, 10 Sep 2018, Kevin Hrpcek wrote:Update for the list archive. I went ahead and finished the mimic upgrade with the osds in a fluctuating state of up and down. The cluster did start to normalize a lot easier after everything was on mimic since the random mass OSD heartbeat failures stopped and the constant mon election problem went away. I'm still battling with the cluster reacting poorly to host reboots or small map changes, but I feel like my current pg:osd ratio may be playing a factor in that since we are 2x normal pg count while migrating data to new EC pools. I'm not sure of the root cause but it seems like the mix of luminous and mimic did not play well together for some reason. Maybe it has to do with the scale of my cluster, 871 osd, or maybe I've missed some some tuning as my cluster has scaled to this size. Kevin On 09/09/2018 12:49 PM, Kevin Hrpcek wrote:Nothing too crazy for non default settings. Some of those osd settings were in place while I was testing recovery speeds and need to be brought back closer to defaults. I was setting nodown before but it seems to mask the problem. While its good to stop the osdmap changes, OSDs would come up, get marked up, but at some point go down again (but the process is still running) and still stay up in the map. Then when I'd unset nodown the cluster would immediately mark 250+ osd down again and i'd be back where I started. This morning I went ahead and finished the osd upgrades to mimic to remove that variable. I've looked for networking problems but haven't found any. 2 of the mons are on the same switch. I've also tried combinations of shutting down a mon to see if a single one was the problem, but they keep electing no matter the mix of them that are up. Part of it feels like a networking problem but I haven't been able to find a culprit yet as everything was working normally before starting the upgrade. Other than the constant mon elections, yesterday I had the cluster 95% healthy 3 or 4 times, but it doesn't last long since at some point the OSDs start trying to fail each other through their heartbeats. 2018-09-09 17:37:29.079 7eff774f5700 1 mon.sephmon1@0(leader).osd e991282 prepare_failure osd.39 10.1.9.2:6802/168438 from osd.49 10.1.9.3:6884/317908 is reporting failure:1 2018-09-09 17:37:29.079 7eff774f5700 0 log_channel(cluster) log [DBG] : osd.39 10.1.9.2:6802/168438 reported failed by osd.49 10.1.9.3:6884/317908 2018-09-09 17:37:29.083 7eff774f5700 1 mon.sephmon1@0(leader).osd e991282 prepare_failure osd.93 10.1.9.9:6853/287469 from osd.372 10.1.9.13:6801/275806 is reporting failure:1 I'm working on getting things mostly good again with everything on mimic and will see if it behaves better. Thanks for your input on this David. [global] mon_initial_members = sephmon1, sephmon2, sephmon3 mon_host = 10.1.9.201,10.1.9.202,10.1.9.203 auth_cluster_required = cephx auth_service_required = cephx auth_client_required = cephx filestore_xattr_use_omap = true public_network = 10.1.0.0/16 osd backfill full ratio = 0.92 osd failsafe nearfull ratio = 0.90 osd max object size = 21474836480 mon max pg per osd = 350 [mon] mon warn on legacy crush tunables = false mon pg warn max per osd = 300 mon osd down out subtree limit = host mon osd nearfull ratio = 0.90 mon osd full ratio = 0.97 mon health preluminous compat warning = false osd heartbeat grace = 60 rocksdb cache size = 1342177280 [mds] mds log max segments = 100 mds log max expiring = 40 mds bal fragment size max = 200000 mds cache memory limit = 4294967296 [osd] osd mkfs options xfs = -i size=2048 -d su=512k,sw=1 osd recovery delay start = 30 osd recovery max active = 5 osd max backfills = 3 osd recovery threads = 2 osd crush initial weight = 0 osd heartbeat interval = 30 osd heartbeat grace = 60 On 09/08/2018 11:24 PM, David Turner wrote:What osd/mon/etc config settings do you have that are not default? It might be worth utilizing nodown to stop osds from marking each other down and finish the upgrade to be able to set the minimum osd version to mimic. Stop the osds in a node, manually mark them down, start them back up in mimic. Depending on how bad things are, setting pause on the cluster to just finish the upgrade faster might not be a bad idea either. This should be a simple question, have you confirmed that there are no networking problems between the MONs while the elections are happening? On Sat, Sep 8, 2018, 7:52 PM Kevin Hrpcek <kevin.hrpcek@xxxxxxxxxxxxx <mailto:kevin.hrpcek@xxxxxxxxxxxxx>> wrote: Hey Sage, I've posted the file with my email address for the user. It is with debug_mon 20/20, debug_paxos 20/20, and debug ms 1/5. The mons are calling for elections about every minute so I let this run for a few elections and saw this node become the leader a couple times. Debug logs start around 23:27:30. I had managed to get about 850/857 osds up, but it seems that within the last 30 min it has all gone bad again due to the OSDs reporting each other as failed. We relaxed the osd_heartbeat_interval to 30 and osd_heartbeat_grace to 60 in an attempt to slow down how quickly OSDs are trying to fail each other. I'll put in the rocksdb_cache_size setting. Thanks for taking a look. Kevin On 09/08/2018 06:04 PM, Sage Weil wrote: |
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