> I tried putting Flashcache on my spindle OSDs using an Intel SSL and it works > great. > This is getting me read and write SSD caching instead of just write > performance on the journal. > It should also allow me to protect the OSD journal on the same drive as the > OSD data and still get benefits of SSD caching for writes.
Small note that on Red Hat based distro's + Flashcache + XFS: There is a major issue (kernel panics) running xfs + flashcache on a 6.4 kernel. (anything higher then 2.6.32-279) It should be fixed in kernel 2.6.32-387.el6 which, I assume, will be 6.5 which only just entered Beta. Fore more info, take a look here: https://github.com/facebook/flashcache/issues/113 Since I've hit this issue (thankfully in our dev environment) we are slightly less enthusiastic about running flashcache :( It also adds a layer of complexity so I would rather just run the journals on SSD, at least on Redhat. I'm not sure about the performance difference of just journals v.s. Flashcache but I'd be happy to read any such comparison :) Also, if you want to make use of the SSD trim func P.S. My experience with Flashcache is on Openstack Swift & Nova not Ceph.
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