Hi,
1 - rados or rbd bug ? We're using rados bench.
2 - This is not bandwith related. If it was, it should happen almost
instantly and not 15 minutes after I start to write to the pool.
Once it has happened on the pool, I can then reproduce with a fewer
--concurrent-ios, like 12 or even 1.
This happens with :
OSDs journals on SSDs with the SAS drives in Raid0 writeback with XFS
and split/merge threshold 10/2 (default)
OSDs journals on SSDs with the SAS drives in Raid0 writeback with XFS
and split/merge threshold 40/8
OSDs journals on SSDs with the SAS drives in Raid0 writeback with btrfs
and split/merge threshold 10/2 (default)
OSDs journals on SAS drives (not using the SSDs) in Raid0 writeback with
XFS and split/merge threshold 10/2 (default)
OSDs journals on SAS drives (not using the SSDs) in Raid0 write-through
with XFS and split/merge threshold 10/2 (default). PERC H730p mini is
not the culprit apparently.
I tried with bluestore but OSDs wouldn't launch (even with an
experimental ... = * set. I suppose its disabled within RHCS 2.0) so I
couldn't tell if this is filestore related.
When the rados bench stops writing, we can see slow requests, and one or
more SAS drives hitting 100% iostat usage, even with --concurrent-ios=1.
With full debug on this particular OSD, we don't see any filestore
operation anymore.
Just some recurring sched_scrub task and then some :
-25> 2016-12-16 10:08:41.891756 7f8855051700 1 heartbeat_map
is_healthy 'FileStore::op_tp thread 0x7f8865903700' had timed out after 60
-24> 2016-12-16 10:08:41.891758 7f8855051700 1 heartbeat_map
is_healthy 'FileStore::op_tp thread 0x7f8866104700' had timed out after 60
-23> 2016-12-16 10:08:41.891759 7f8855051700 1 heartbeat_map
is_healthy 'FileStore::op_tp thread 0x7f885f0f6700' had timed out after 60
-22> 2016-12-16 10:08:41.891772 7f8856b57700 1 heartbeat_map
is_healthy 'OSD::osd_op_tp thread 0x7f8842f10700' had timed out after 15
-21> 2016-12-16 10:08:41.891775 7f8856b57700 1 heartbeat_map
is_healthy 'OSD::osd_op_tp thread 0x7f884641b700' had timed out after 15
-20> 2016-12-16 10:08:41.891777 7f8856b57700 1 heartbeat_map
is_healthy 'FileStore::op_tp thread 0x7f885f8f7700' had timed out after 60
-19> 2016-12-16 10:08:41.891779 7f8856b57700 1 heartbeat_map
is_healthy 'FileStore::op_tp thread 0x7f88600f8700' had timed out after 60
then the OSD hit the suicide timeout :
0> 2016-12-16 10:08:42.031740 7f8856b57700 -1
common/HeartbeatMap.cc: In function 'bool
ceph::HeartbeatMap::_check(const ceph::heartbeat_handle_d*, const char*,
time_t)' thread 7f8856b57700 time 2016-12-16 10:08:42.029391
common/HeartbeatMap.cc: 86: FAILED assert(0 == "hit suicide timeout")
ceph version 10.2.2-41.el7cp (1ac1c364ca12fa985072174e75339bfb1f50e9ee)
1: (ceph::__ceph_assert_fail(char const*, char const*, int, char
const*)+0x85) [0x7f887873be25]
2: (ceph::HeartbeatMap::_check(ceph::heartbeat_handle_d const*, char
const*, long)+0x2e1) [0x7f88786783a1]
3: (ceph::HeartbeatMap::is_healthy()+0xde) [0x7f8878678bfe]
4: (OSD::handle_osd_ping(MOSDPing*)+0x93f) [0x7f88780b206f]
5: (OSD::heartbeat_dispatch(Message*)+0x3cb) [0x7f88780b329b]
6: (DispatchQueue::entry()+0x78a) [0x7f88787fcd0a]
7: (DispatchQueue::DispatchThread::entry()+0xd) [0x7f887871761d]
8: (()+0x7dc5) [0x7f887666adc5]
9: (clone()+0x6d) [0x7f8874cf673d]
NOTE: a copy of the executable, or `objdump -rdS <executable>` is
needed to interpret this.
--- logging levels ---
0/ 5 none
0/ 1 lockdep
0/ 1 context
1/ 1 crush
1/ 5 mds
1/ 5 mds_balancer
1/ 5 mds_locker
[...]
1/ 5 kstore
4/ 5 rocksdb
4/ 5 leveldb
1/ 5 kinetic
1/ 5 fuse
-2/-2 (syslog threshold)
-1/-1 (stderr threshold)
max_recent 10000
max_new 1000
log_file /var/log/ceph/ceph-osd.16.log
--- end dump of recent events ---
and comes back to life on its own 2'42" later.
We use ceph version 10.2.2-41.el7cp
(1ac1c364ca12fa985072174e75339bfb1f50e9ee) (RHCS 2.0).
We're hitting something here.
Regards,
Frederic.
Le 15/12/2016 à 21:04, Vincent Godin a écrit :
Hello,
I didn't look at your video but i already can tell you some tracks :
1 - there is a bug in 10.2.2 which make the client cache not working.
The client cache works as it never recieved a flush so it will stay in
writethrough mode. This bug is clear in 10.2.3
2 - 2 SSDs in JBOD and 12 x 4TB NL SAS in RAID0 are not very well
optimized if your workload is based on write. You will perform in
write at the max speed of your two SSD only. I don't know the real
speed of your SSD nor your SAS disks but let's say:
your SSD can reach a 400 MB/s in write throughput
your SAS can reach a 130 MB/s in write throughput
i suppose that you use 1 SSD to host the journals of 6 SAS
Your max throughput in write will be 2 x 400 MB/s so 800 MB/s compare
to the 12 x 130 MB/s = 1560 MB/s of your SAS
if you had 4 SSD for the journal, 1 SSD for 3 SAS
Your max throughput would be 4 x 400 MB/s so 1600 MB/s very near of
the 1560 MB/s of your SAS
Of course, you need to adjust that with the real throughput of your
SSD ans SAS disks
Vincent
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