|
On 11/08/2019 19:46, Victor Hooi wrote:
Generally i would go with adding the SSDs, gives you good capacity + overall performance per dollar + its common deployment in Ceph. Ceph does have overhead so trying to push extreme performance may be costly. To answer your questions: Latency and single stream iops will always be better with pure Optane. So if you have a few client streams / low queue depth, then adding SSDs will make it slower. If you have a lot of client streams, you can get higher total iops if you add SSDs and use your Optane as WAL/DB. 4 SSDs could be in the ballpark but you can stress test you cluster and measure the %busy of all your disks ( Optane + SSDs) to make sure they are equally busy at that ratio, if your Optane is less busy, you can further add SSDs, increasing overall iops. So performance will depend if you want highest iops + can
sacrifice latency then a hybrid solution is better. If you need
absolute latency then stay with all Optane. As stated Ceph does
have overhead, so the gain in latency as a ratio is costly. For caching: i would not recommed bcache/dm-cache unless for hdds. Possibly dm-writecache can show slight write latency improvements and maybe a middle ground if you really want to squeeze latency. /Maged
|
_______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
