Hi Stefan,
so (surprise!) some DB access counters show a significant difference, e.g.
"kv_flush_lat": {
"avgcount": 1423,
"sum": 0.000906419,
"avgtime": 0.000000636
},
"kv_sync_lat": {
"avgcount": 1423,
"sum": 0.712888091,
"avgtime": 0.000500975
},
vs.
"kv_flush_lat": {
"avgcount": 1146,
"sum": 3.346228802,
"avgtime": 0.002919920
},
"kv_sync_lat": {
"avgcount": 1146,
"sum": 3.754915016,
"avgtime": 0.003276540
},
Also for bluefs:
"bytes_written_sst": 0,
vs.
"bytes_written_sst": 59785361,
Could you please rerun these benchmark/perf counter gathering steps a couple more times and check if the difference is persistent.
If that's particularly true for "kv_flush_lat" counter - please rerun with debug-bluefs set to 20 and collect OSD logs for both cases.
Thanks,
Igor
On 5/5/2020 11:46 AM, Stefan Priebe - Profihost AG wrote:
Hello Igor,
Am 30.04.20 um 15:52 schrieb Igor Fedotov:
1) reset perf counters for the specific OSD
2) run bench
3) dump perf counters.
This is OSD 0:
# ceph tell osd.0 bench -f plain 12288000 4096
bench: wrote 12 MiB in blocks of 4 KiB in 6.70482 sec at 1.7 MiB/sec 447
IOPS
https://pastebin.com/raw/hbKcU07g
This is OSD 38:
# ceph tell osd.38 bench -f plain 12288000 4096
bench: wrote 12 MiB in blocks of 4 KiB in 2.01763 sec at 5.8 MiB/sec
1.49k IOPS
https://pastebin.com/raw/Tx2ckVm1
Collecting disks' (both main and db) activity with iostat would be nice
too. But please either increase benchmark duration or reduce iostat
probe period to 0.1 or 0.05 second
This gives me:
# ceph tell osd.38 bench -f plain 122880000 4096
Error EINVAL: 'count' values greater than 12288000 for a block size of 4
KiB, assuming 100 IOPS, for 30 seconds, can cause ill effects on osd.
Please adjust 'osd_bench_small_size_max_iops' with a higher value if you
wish to use a higher 'count'.
Stefan
Thanks,
Igor
On 4/28/2020 8:42 PM, Stefan Priebe - Profihost AG wrote:
HI Igor,
but the performance issue is still present even on the recreated OSD.
# ceph tell osd.38 bench -f plain 12288000 4096
bench: wrote 12 MiB in blocks of 4 KiB in 1.63389 sec at 7.2 MiB/sec
1.84k IOPS
vs.
# ceph tell osd.10 bench -f plain 12288000 4096
bench: wrote 12 MiB in blocks of 4 KiB in 10.7454 sec at 1.1 MiB/sec 279
IOPS
both baked by the same SAMSUNG SSD as block.db.
Greets,
Stefan
Am 28.04.20 um 19:12 schrieb Stefan Priebe - Profihost AG:
Hi Igore,
Am 27.04.20 um 15:03 schrieb Igor Fedotov:
Just left a comment at https://tracker.ceph.com/issues/44509
Generally bdev-new-db performs no migration, RocksDB might
eventually do
that but no guarantee it moves everything.
One should use bluefs-bdev-migrate to do actual migration.
And I think that's the root cause for the above ticket.
perfect - this removed all spillover in seconds.
Greets,
Stefan
Thanks,
Igor
On 4/24/2020 2:37 PM, Stefan Priebe - Profihost AG wrote:
No not a standalone Wal I wanted to ask whether bdev-new-db migrated
dB and Wal from hdd to ssd.
Stefan
Am 24.04.2020 um 13:01 schrieb Igor Fedotov <ifedotov@xxxxxxx>:
Unless you have 3 different types of disks beyond OSD (e.g. HDD, SSD,
NVMe) standalone WAL makes no sense.
On 4/24/2020 1:58 PM, Stefan Priebe - Profihost AG wrote:
Is Wal device missing? Do I need to run *bluefs-bdev-new-db and
Wal?*
Greets,
Stefan
Am 24.04.2020 um 11:32 schrieb Stefan Priebe - Profihost AG
<s.priebe@xxxxxxxxxxxx>:
Hi Igor,
there must be a difference. I purged osd.0 and recreated it.
Now it gives:
ceph tell osd.0 bench
{
"bytes_written": 1073741824,
"blocksize": 4194304,
"elapsed_sec": 8.1554735639999993,
"bytes_per_sec": 131659040.46819863,
"iops": 31.389961354303033
}
What's wrong wiht adding a block.db device later?
Stefan
Am 23.04.20 um 20:34 schrieb Stefan Priebe - Profihost AG:
Hi,
if the OSDs are idle the difference is even more worse:
# ceph tell osd.0 bench
{
"bytes_written": 1073741824,
"blocksize": 4194304,
"elapsed_sec": 15.396707875000001,
"bytes_per_sec": 69738403.346825853,
"iops": 16.626931034761871
}
# ceph tell osd.38 bench
{
"bytes_written": 1073741824,
"blocksize": 4194304,
"elapsed_sec": 6.8903985170000004,
"bytes_per_sec": 155831599.77624846,
"iops": 37.153148597776521
}
Stefan
Am 23.04.20 um 14:39 schrieb Stefan Priebe - Profihost AG:
Hi,
Am 23.04.20 um 14:06 schrieb Igor Fedotov:
I don't recall any additional tuning to be applied to new DB
volume. And assume the hardware is pretty the same...
Do you still have any significant amount of data spilled over
for these updated OSDs? If not I don't have any valid
explanation for the phenomena.
just the 64k from here:
https://tracker.ceph.com/issues/44509
You might want to try "ceph osd bench" to compare OSDs under
pretty the same load. Any difference observed
Servers are the same HW. OSD Bench is:
# ceph tell osd.0 bench
{
"bytes_written": 1073741824,
"blocksize": 4194304,
"elapsed_sec": 16.091414781000001,
"bytes_per_sec": 66727620.822242722,
"iops": 15.909104543266945
}
# ceph tell osd.36 bench
{
"bytes_written": 1073741824,
"blocksize": 4194304,
"elapsed_sec": 10.023828538,
"bytes_per_sec": 107118933.6419194,
"iops": 25.539143953780986
}
OSD 0 is a Toshiba MG07SCA12TA SAS 12G
OSD 36 is a Seagate ST12000NM0008-2H SATA 6G
SSDs are all the same like the rest of the HW. But both drives
should give the same performance from their specs. The only other
difference is that OSD 36 was directly created with the block.db
device (Nautilus 14.2.7) and OSD 0 (14.2.8) does not.
Stefan
On 4/23/2020 8:35 AM, Stefan Priebe - Profihost AG wrote:
Hello,
is there anything else needed beside running:
ceph-bluestore-tool --path /var/lib/ceph/osd/ceph-${OSD}
bluefs-bdev-new-db --dev-target /dev/vgroup/lvdb-1
I did so some weeks ago and currently i'm seeing that all osds
originally deployed with --block-db show 10-20% I/O waits while
all those got converted using ceph-bluestore-tool show 80-100%
I/O waits.
Also is there some tuning available to use more of the SSD? The
SSD (block-db) is only saturated at 0-2%.
Greets,
Stefan
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