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(a)ceph.io
>>>> To unsubscribe send an email to ceph-users-leave(a)ceph.io