After some testing (doing heavy IO on a rdb-based VM with hung_task_timeout_secs=1 while manually requesting deep-scrubs on the underlying pgs (as determined via rados ls->osdmaptool), I don’t think scrubbing is the cause.
At least, I can’t make it happen this way… although I can’t *always* make it happen whileeither. I will continue testing as above, but suggestions on improved test methodology are welcome.
We occasionally see blocked requests in a running log (ceph –w > log), but not correlated with hung VM IO. Scrubbing doesn’t seem correlated either.
--
Eric
On 6/21/17, 2:55 PM, "Jason Dillaman" <jdillama@xxxxxxxxxx> wrote:
Do your VMs or OSDs show blocked requests? If you disable scrub or
restart the blocked OSD, does the issue go away? If yes, it most
likely is this issue [1].
[1] http://tracker.ceph.com/issues/20041
On Wed, Jun 21, 2017 at 3:33 PM, Hall, Eric <eric.hall@xxxxxxxxxxxxxx> wrote:
> The VMs are using stock Ubuntu14/16 images so yes, there is the default “/sbin/fstrim –all” in /etc/cron.weekly/fstrim.
>
> --
> Eric
>
> On 6/21/17, 1:58 PM, "Jason Dillaman" <jdillama@xxxxxxxxxx> wrote:
>
> Are some or many of your VMs issuing periodic fstrims to discard
> unused extents?
>
> On Wed, Jun 21, 2017 at 2:36 PM, Hall, Eric <eric.hall@xxxxxxxxxxxxxx> wrote:
> > After following/changing all suggested items (turning off exclusive-lock
> > (and associated object-map and fast-diff), changing host cache behavior,
> > etc.) this is still a blocking issue for many uses of our OpenStack/Ceph
> > installation.
> >
> >
> >
> > We have upgraded Ceph to 10.2.7, are running 4.4.0-62 or later kernels on
> > all storage, compute hosts, and VMs, with libvirt 1.3.1 on compute hosts.
> > Have also learned quite a bit about producing debug logs. ;)
> >
> >
> >
> > I’ve followed the related threads since March with bated breath, but still
> > find no resolution.
> >
> >
> >
> > Previously, I got pulled away before I could produce/report discussed debug
> > info, but am back on the case now. Please let me know how I can help
> > diagnose and resolve this problem.
> >
> >
> >
> > Any assistance appreciated,
> >
> > --
> >
> > Eric
> >
> >
> >
> > On 3/28/17, 3:05 AM, "Marius Vaitiekunas" <mariusvaitiekunas@xxxxxxxxx>
> > wrote:
> >
> >
> >
> >
> >
> >
> >
> > On Mon, Mar 27, 2017 at 11:17 PM, Peter Maloney
> > <peter.maloney@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > I can't guarantee it's the same as my issue, but from that it sounds the
> > same.
> >
> > Jewel 10.2.4, 10.2.5 tested
> > hypervisors are proxmox qemu-kvm, using librbd
> > 3 ceph nodes with mon+osd on each
> >
> > -faster journals, more disks, bcache, rbd_cache, fewer VMs on ceph, iops
> > and bw limits on client side, jumbo frames, etc. all improve/smooth out
> > performance and mitigate the hangs, but don't prevent it.
> > -hangs are usually associated with blocked requests (I set the complaint
> > time to 5s to see them)
> > -hangs are very easily caused by rbd snapshot + rbd export-diff to do
> > incremental backup (one snap persistent, plus one more during backup)
> > -when qemu VM io hangs, I have to kill -9 the qemu process for it to
> > stop. Some broken VMs don't appear to be hung until I try to live
> > migrate them (live migrating all VMs helped test solutions)
> >
> > Finally I have a workaround... disable exclusive-lock, object-map, and
> > fast-diff rbd features (and restart clients via live migrate).
> > (object-map and fast-diff appear to have no effect on dif or export-diff
> > ... so I don't miss them). I'll file a bug at some point (after I move
> > all VMs back and see if it is still stable). And one other user on IRC
> > said this solved the same problem (also using rbd snapshots).
> >
> > And strangely, they don't seem to hang if I put back those features,
> > until a few days later (making testing much less easy...but now I'm very
> > sure removing them prevents the issue)
> >
> > I hope this works for you (and maybe gets some attention from devs too),
> > so you don't waste months like me.
> >
> >
> > On 03/27/17 19:31, Hall, Eric wrote:
> >> In an OpenStack (mitaka) cloud, backed by a ceph cluster (10.2.6 jewel),
> >> using libvirt/qemu (1.3.1/2.5) hypervisors on Ubuntu 14.04.5 compute and
> >> ceph hosts, we occasionally see hung processes (usually during boot, but
> >> otherwise as well), with errors reported in the instance logs as shown
> >> below. Configuration is vanilla, based on openstack/ceph docs.
> >>
> >> Neither the compute hosts nor the ceph hosts appear to be overloaded in
> >> terms of memory or network bandwidth, none of the 67 osds are over 80% full,
> >> nor do any of them appear to be overwhelmed in terms of IO. Compute hosts
> >> and ceph cluster are connected via a relatively quiet 1Gb network, with an
> >> IBoE net between the ceph nodes. Neither network appears overloaded.
> >>
> >> I don’t see any related (to my eye) errors in client or server logs, even
> >> with 20/20 logging from various components (rbd, rados, client,
> >> objectcacher, etc.) I’ve increased the qemu file descriptor limit
> >> (currently 64k... overkill for sure.)
> >>
> >> I “feels” like a performance problem, but I can’t find any capacity issues
> >> or constraining bottlenecks.
> >>
> >> Any suggestions or insights into this situation are appreciated. Thank
> >> you for your time,
> >> --
> >> Eric
> >>
> >>
> >> [Fri Mar 24 20:30:40 2017] INFO: task jbd2/vda1-8:226 blocked for more
> >> than 120 seconds.
> >> [Fri Mar 24 20:30:40 2017] Not tainted 3.13.0-52-generic #85-Ubuntu
> >> [Fri Mar 24 20:30:40 2017] "echo 0 >
> >> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >> [Fri Mar 24 20:30:40 2017] jbd2/vda1-8 D ffff88043fd13180 0 226
> >> 2 0x00000000
> >> [Fri Mar 24 20:30:40 2017] ffff88003728bbd8 0000000000000046
> >> ffff880426900000 ffff88003728bfd8
> >> [Fri Mar 24 20:30:40 2017] 0000000000013180 0000000000013180
> >> ffff880426900000 ffff88043fd13a18
> >> [Fri Mar 24 20:30:40 2017] ffff88043ffb9478 0000000000000002
> >> ffffffff811ef7c0 ffff88003728bc50
> >> [Fri Mar 24 20:30:40 2017] Call Trace:
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff811ef7c0>] ?
> >> generic_block_bmap+0x50/0x50
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff81726d2d>] io_schedule+0x9d/0x140
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff811ef7ce>] sleep_on_buffer+0xe/0x20
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff817271b2>] __wait_on_bit+0x62/0x90
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff811ef7c0>] ?
> >> generic_block_bmap+0x50/0x50
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff81727257>]
> >> out_of_line_wait_on_bit+0x77/0x90
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff810ab180>] ?
> >> autoremove_wake_function+0x40/0x40
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff811f0afa>]
> >> __wait_on_buffer+0x2a/0x30
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8128bb4d>]
> >> jbd2_journal_commit_transaction+0x185d/0x1ab0
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff810755df>] ?
> >> try_to_del_timer_sync+0x4f/0x70
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8128fe7d>] kjournald2+0xbd/0x250
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff810ab140>] ?
> >> prepare_to_wait_event+0x100/0x100
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8128fdc0>] ?
> >> commit_timeout+0x10/0x10
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8108b5d2>] kthread+0xd2/0xf0
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8108b500>] ?
> >> kthread_create_on_node+0x1c0/0x1c0
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8173304c>] ret_from_fork+0x7c/0xb0
> >> [Fri Mar 24 20:30:40 2017] [<ffffffff8108b500>] ?
> >> kthread_create_on_node+0x1c0/0x1c0
> >>
> >>
> >>
> >> _______________________________________________
> >> ceph-users mailing list
> >> ceph-users@xxxxxxxxxxxxxx
> >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
> >
> > _______________________________________________
> > ceph-users mailing list
> > ceph-users@xxxxxxxxxxxxxx
> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
> >
> >
> > Hi,
> >
> >
> >
> > We are using these settings on hypervisors in openstack:
> >
> > vm.dirty_ratio = 40
> >
> > vm.dirty_background_ratio = 5
> >
> >
> >
> > And these on vms:
> >
> > vm.dirty_ratio = 10
> >
> > vm.dirty_background_ratio = 5
> >
> >
> >
> > In our case it prevents vms from crashing.
> >
> >
> >
> > --
> >
> > Marius Vaitiekūnas
> >
> >
> > _______________________________________________
> > ceph-users mailing list
> > ceph-users@xxxxxxxxxxxxxx
> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
>
>
>
> --
> Jason
>
>
--
Jason
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