Hello, On Wed, 20 Jul 2016 15:36:34 +0200 Götz Reinicke - IT Koordinator wrote: > Hi, > > currently there are two levels I know of: storage- and cachepool. From > our workload I do expect an third "level" of data, which will stay > currently in the storagepool as well. > > Has anyone as we been thinking of data which could be moved even deeper > in that tiering, e.g. have SSD cache, fast lots of HDD SAS something > 2-4TB size for storage pool and e.g. 8TB so whatever for an "archive" level? > > From my pov that would be for data which are good and nice to have in > the cluster, but dont have to be as reliable and fast as the storage > tier data. > The later, in particular the reliability bit would be playing with fire. Imagine your most valuable database file, of which some parts are rarely accessed, while others are constantly being written or read. So some 4MB Ceph objects would be in the SSD cache-pool, some in the normal one and others in the "cold" one. Now your cold storage with just 2 replicas suffers a double disk failure and your DB file is dead as a dodo, at least eventually If your cold storage were to be just as reliable as the rest, that concept could work, but still lead to surprises, for example when booting a VM after a long with most of its data having been pushed to the slow pool. > Or may be that kind of data could be moved to a LTO tape library ... > just thinking ! :) > A dedicated pool (something with replica 1 or 2 and backed by RAID6 OSDs for example or an EC pool) and "manual" moving would likely be better suited than the approach above. Christian > Thanks for feedback and suggestion on how to handle data you "never will > use again but you have to have them" :) > > Regards . Götz > > > > -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Global OnLine Japan/Rakuten Communications http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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