I can only think of 1 type of cache tier usage that is faster if you are using the cache tier on the same root of osds as the EC pool. That is cold storage where the file is written initially, modified and read door the first X hours, and then remains in cold storage for the remainder of its life with rate reads.
Other than that there are a few use cases using a faster root of osds that might make sense, but generally it's still better to utilize that faster storage in the rest of the osd stack either as journals for filestore or Wal/DB partitions for bluestore. On Sat, Sep 30, 2017, 12:56 PM Chad William Seys <cws...@physics.wisc.edu> wrote: > Hi all, > Now that Luminous supports direct writing to EC pools I was wondering > if one can get more performance out of an erasure-coded pool with > overwrites or an erasure-coded pool with a cache tier? > I currently have a 3 replica pool in front of a k2m2 erasure coded > pool. Luminous documentation on cache tiering > > http://docs.ceph.com/docs/luminous/rados/operations/cache-tiering/#a-word-of-caution > makes it sound like cache tiering is usually not recommonded. > > Thanks! > Chad. > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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