Hi Stefan, hmm... could you please collect performance counters for these two cases. Using the following sequence 1) reset perf counters for the specific OSD 2) run bench 3) dump perf counters. 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 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:
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.
Hi Igore, Am 27.04.20 um 15:03 schrieb Igor Fedotov: 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@suse.de>:
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@profihost.ag>: > > 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 >>>>> _______________________________________________ >>>>> ceph-users mailing list -- ceph-users@ceph.io >>>>> To unsubscribe send an email to ceph-users-leave@ceph.io