On Mon, Aug 5, 2019 at 6:35 PM <vitalif@xxxxxxxxxx> wrote:
> Hi Team,
> @vitalif@xxxxxxxxxx , thank you for information and could you please
> clarify on the below quires as well,
>
> 1. Average object size we use will be 256KB to 512KB , will there be
> deferred write queue ?
With the default settings, no (bluestore_prefer_deferred_size_hdd =
32KB)
Are you sure that 256-512KB operations aren't counted as multiple
operations in your disk stats?
I think it is not taking multiple operations.
> 2. Share the link of existing rocksdb ticket which does 2 write +
> syncs.
My PR is here https://github.com/ceph/ceph/pull/26909, you can find the
issue tracker links inside it.
> 3. Any configuration by which we can reduce/optimize the iops ?
As already said part of your I/O may be caused by the metadata (rocksdb)
reads if it doesn't fit into RAM. You can try to add more RAM in that
case... :)
I can add RAM ans is there a way to increase rocksdb caching , can I increase bluestore_cache_size_hdd to higher value to cache rocksdb?
You can also try to add SSDs for metadata (block.db/block.wal).
This we have planned to add some SSDs and how many OSD's rocks db we can add per SSDs and i guess if one SSD is down then all related OSDs has to be re-installed.
Is there something else?... I don't think so.
--
Vitaliy Filippov
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