On Mon, Mar 01, 2021 at 12:37:38PM +0800, Norman.Kern wrote: > Hi, guys > > I am testing ceph on bcache devices, I found the performance is not > good as expected. Does anyone have any best practices for it? Thanks.
Hi, sorry to say, but since use cases and workloads differ so much, there is no easy list of best practises. Number one reason for low bcache performance is consumer-grade caching devices, since bcache does a lot of write amplification and not even "PRO" consumer devices will give you decent and consistent performance. You might even end up with worse performance than on direct HDD under load. With decent caching device, there still are quite a few tuning knobs in bcache, but it all depends on your workload. You also have to consider the added complexity of a bcache setup for maintenance operations. Moving an OSD between hosts becomes a complex operation (wait for bcache draining, detach bcache, move HDD, create new bcache caching device, attach bcache). Regards Matthias _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
