On Thu, Mar 5, 2020 at 3:31 PM Wido den Hollander <wido@xxxxxxxx> wrote: > > > > On 3/5/20 3:22 PM, Sage Weil wrote: > > On Thu, 5 Mar 2020, Dan van der Ster wrote: > >> Hi all, > >> > >> There's something broken in our env when we try to add new mons to > >> existing clusters, confirmed on two clusters running mimic and > >> nautilus. It's basically this issue > >> https://tracker.ceph.com/issues/42830 > >> > >> In case something is wrong with our puppet manifests, I'm trying to > >> doing it manually. > >> > >> First we --mkfs the mon and start it, but as soon as the new mon > >> starts synchronizing, the existing leader becomes unresponsive and an > >> election is triggered. > >> > >> Here's exactly what I'm doing: > >> > >> # cd /var/lib/ceph/tmp/ > >> # scp cephmon1:/var/lib/ceph/tmp/keyring.mon.cephmon1 keyring.mon.cephmon4 > >> # ceph mon getmap -o monmap > >> # ceph-mon --mkfs -i cephmon4 --monmap monmap --keyrin > >> keyring.mon.cephmon4 --setuser ceph --setgroup ceph > >> # vi /etc/ceph/ceph.conf <add the new mon to ceph.conf like this> > >> [mon.cephmon4] > >> host = cephmon4 > >> mon addr = a.b.c.d:6790 > >> # systemctl start ceph-mon@cephmon4 > >> > >> The log file on the new mon shows it start synchronizing, then > >> immediately the CPU usage on the leader goes to 100% and elections > >> start happening, and ceph health shows mon slow ops. perf top of the > >> ceph-mon with 100% CPU is shown below [1]. > >> On a small nautilus cluster, the new mon gets added withing a minute > >> or so (but not cleanly -- the leader is unresponsive for quite awhile > >> until the new mon joins). debug_mon=20 on the leader doesn't show > >> anything very interesting. > >> On our large mimic cluster we tried waiting more than 10 minutes -- > >> suffering through several mon elections and 100% usage bouncing around > >> between leaders -- until we gave up. > >> > >> I'm pulling my hair out a bit on this -- it's really weird! > > > > Can you try running a rocksdb compaction on the existing mons before > > adding the new one and see if that helps? > > I can chime in here: I had this happen to a customer as well. > > Compact did not work. > > Some background: > > 5 Monitors and the DBs were ~350M in size. They upgraded one MON from > 13.2.6 to 13.2.8 and that caused one MON (sync source) to eat 100% CPU. > > The logs showed that the upgraded MON (which was restarted) was in the > synchronizing state. > > Because they had 5 MONs they now had 3 left so the cluster kept running. > > I left this for about 5 minutes, but it never synced. > > I tried a compact, didn't work either. > > Eventually I stopped one MON, tarballed it's database and used that to > bring back the MON which was upgraded to 13.2.8 Yeah, that works! -- something like: ceph mon add <newmon> ip:6789 rsync <oldmon>:/var/lib/ceph/mon/ceph.. /var/lib/ceph/mon systemctl start ceph-mon.target I guess that's a workaround, but would be good to find out why the sync source is spinning. -- dan > > That work without any hickups. The MON joined again within a few seconds. > > Wido > > > > > s > > > >> > >> Did anyone add a new mon to an existing large cluster recently, and it > >> went smoothly? > >> > >> Cheers, Dan > >> > >> [1] > >> > >> 15.12% ceph-mon [.] > >> MonitorDBStore::Transaction::encode > >> 8.95% libceph-common.so.0 [.] > >> ceph::buffer::v14_2_0::ptr::append > >> 8.68% libceph-common.so.0 [.] > >> ceph::buffer::v14_2_0::list::append > >> 7.69% libceph-common.so.0 [.] > >> ceph::buffer::v14_2_0::ptr::release > >> 5.86% libceph-common.so.0 [.] > >> ceph::buffer::v14_2_0::ptr::ptr > >> _______________________________________________ > >> 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 > > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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