On 4/10/19 9:25 AM, jes...@krogh.cc wrote:
>> On 4/10/19 9:07 AM, Charles Alva wrote:
>>> Hi Ceph Users,
>>>
>>> Is there a way around to minimize rocksdb compacting event so that it
>>> won't use all the spinning disk IO utilization and avoid it being marked
>>> as down due to fail to send heartbeat to others?
>>>
>>> Right now we have frequent high IO disk utilization for every 20-25
>>> minutes where the rocksdb reaches level 4 with 67GB data to compact.
>>>
>>
>> How big is the disk? RocksDB will need to compact at some point and it
>> seems that the HDD can't keep up.
>>
>> I've seen this with many customers and in those cases we offloaded the
>> WAL+DB to an SSD.
>
> Guess the SSD need to be pretty durable to handle that?
>
Always use DC-grade SSDs, but you don't need to buy the most expensive
ones you can find. ~1.5DWPD is sufficient.
> Is there a "migration path" to offload this or is it needed to destroy
> and re-create the OSD?
>
In Nautilus release (and maybe Mimic) there is a tool to migrate the DB
to a different device without the need to re-create the OSD. This is
bluestore-dev-tool I think.
Wido
> Thanks.
>
> Jesper
>
>
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