| To expand upon this, the very nature and existence of Ceph is to replace RAID. The FS itself replicates data and handles the HA functionality that you're looking for. If you're going to build a single server with all those disks, backed by a ZFS RAID setup, you're going to be much better suited with an iSCSI setup. The idea of ceph is that it takes the place of all the ZFS bells and whistles. A CEPH cluster that only has one OSD backed by that huge ZFS setup becomes just a wire-protocol to speak to the server. The magic in ceph comes from the replication and distribution of the data across many OSDs, hopefully living in many hosts. My own setup for instance uses 96 OSDs that are spread across 4 hosts (I know I know guys - CPU is a big deal with SSDs so 24 per host is a tall order - didn't know that when we built it - been working ok so far) that is then distributed between 2 cabinets on 2 separate cooling/power/data zones in our datacenter. My CRUSH map is currently setup for 3 copies of all data, and laid out so that at least one copy is located in each cabinet, and then the cab that gets the 2 copies also makes sure that each copy is on a different host. No RAID needed because ceph makes sure that I have a "safe" amount of copies of the data, in a distribution layout that allows us to sleep at night. In my opinion, ceph is much more pleasant, powerful, and versatile to deal with than both hardware RAID and ZFS (Both of which we have instances of deployed as well from previous iterations of infrastructure deployments). Now, you could always create small little zRAID clusters using ZFS, and then give an OSD to each of those, if you wanted even an additional layer of safety. Heck, you could even have hardware RAID behind the zRAID, for even another layer. Where YOU need to make the decision is the trade-off between HA functionality/peace of mind, performance, and useability/maintainability. Would me happy to answer any questions you still have... Cheers, -- Stephen Mercier Senior Systems Architect Attainia, Inc. Phone: 866-288-2464 ext. 727 Email: stephen.mercier@xxxxxxxxxxxx Web: www.attainia.com Capital equipment lifecycle planning & budgeting solutions for healthcare On Mar 4, 2015, at 10:42 AM, Alexandre DERUMIER wrote:
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