Hi all,

The only recommendation I can find about db device selection is about the capacity (4% of the data disk) on the documents.  Is there any suggestions about technical specs like throughput, IOPS and db device per data disk?

While designing a specific infrastructure with filestore, we were looking its specs to meet requirements of all the disks behind the journal device. But in bluestore, data is directly written into data device via bluefs adapter while metadata is written into db (RocksDB) device. 

I know that it depends on the workload, but is there any best practice or recommendation about selection of db device? 

IMO, using NVME disks that we used for filestore journals as db devices is not meaningful. Because NVME disks have minimal latency and extraordinary throughput and IOPS performance. So I am not sure that DB device needs that kind of performance. So I want to use those NVME disks for a full flash pool, and choose another disks for db device. 

Any suggestion or recommendation would be appreciated.