An additional side to the RAID question: when you have a box with more drives than you can front with OSDs due to memory or CPU constraints, is some form of RAID advisable? At the moment "one OSD per drive" is the recommendation, but from my perspective this does not scale at high drive densities (e.g 10+ drives per U).
On Thu, Oct 3, 2013 at 11:08 AM, John-Paul Robinson <j...@uab.edu> wrote: > What is this take on such a configuration? > > Is it worth the effort of tracking "rebalancing" at two layers, RAID > mirror and possibly Ceph if the pool has a redundancy policy. Or is it > better to just let ceph rebalance itself when you lose a non-mirrored disk? > > If following the "raid mirror" approach, would you then skip redundency > at the ceph layer to keep your total overhead the same? It seems that > would be risky in the even you loose your storage server with the > raid-1'd drives. No Ceph level redunancy would then be fatal. But if > you do raid-1 plus ceph redundancy, doesn't that mean it takes 4TB for > each 1 real TB? > > ~jpr > > On 10/02/2013 10:03 AM, Dimitri Maziuk wrote: > > I would consider (mdadm) raid-1, dep. on the hardware & budget, > > because this way a single disk failure will not trigger a cluster-wide > > rebalance. > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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