On Tue, Oct 20, 2015 at 3:26 AM, Haomai Wang <haomaiwang@xxxxxxxxx> wrote: > The fact is that journal could help a lot for rbd use cases, > especially for small ios. I don' t think it will be bottleneck. If we > just want to reduce double write, it doesn't solve any performance > problem. > One trick I've been using in my ceph clusters is hiding a slow write backend behind a fast journal device. The write performance will be of the fast (and small) journal device. This only helps on write, but it can make a huge difference. I've even made some tests showing (within 10%, RBD and S3) that the backend device doesn't matter and the write performance is exactly the same as that of the journal device fronting all the writes. _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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