Thank you all for all good advises and much needed documentation. I have a lot to digest :)
Adrian On 03/04/2015 08:17 PM, Stephen Mercier wrote: > 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.merc...@attainia.com <mailto:stephen.merc...@attainia.com> > Web: www.attainia.com <http://www.attainia.com> > > Capital equipment lifecycle planning & budgeting solutions for healthcare > > > > > > > On Mar 4, 2015, at 10:42 AM, Alexandre DERUMIER wrote: > >> Hi for hardware, inktank have good guides here: >> >> http://www.inktank.com/resource/inktank-hardware-selection-guide/ >> http://www.inktank.com/resource/inktank-hardware-configuration-guide/ >> >> ceph works well with multiple osd daemon (1 osd by disk), >> so you should not use raid. >> >> (xfs is the recommended fs for osd daemons). >> >> you don't need disk spare too, juste enough disk space to handle a >> disk failure. >> (datas are replicated-rebalanced on other disks/osd in case of disk >> failure) >> >> >> ----- Mail original ----- >> De: "Adrian Sevcenco" <adrian.sevce...@cern.ch> >> À: "ceph-users" <ceph-users@lists.ceph.com> >> Envoyé: Mercredi 4 Mars 2015 18:30:31 >> Objet: [ceph-users] CEPH hardware recommendations and cluster >> designquestions >> >> Hi! I seen the documentation >> http://ceph.com/docs/master/start/hardware-recommendations/ but those >> minimum requirements without some recommendations don't tell me much ... >> >> So, from what i seen for mon and mds any cheap 6 core 16+ gb ram amd >> would do ... what puzzles me is that "per daemon" construct ... >> Why would i need/require to have multiple daemons? with separate servers >> (3 mon + 1 mds - i understood that this is the requirement) i imagine >> that each will run a single type of daemon.. did i miss something? >> (beside that maybe is a relation between daemons and block devices and >> for each block device should be a daemon?) >> >> for mon and mds : would help the clients if these are on 10 GbE? >> >> for osd : i plan to use a 36 disk server as osd server (ZFS RAIDZ3 all >> disks + 2 ssds mirror for ZIL and L2ARC) - that would give me ~ 132 TB >> how much ram i would really need? (128 gb would be way to much i think) >> (that RAIDZ3 for 36 disks is just a thought - i have also choices like: >> 2 X 18 RAIDZ2 ; 34 disks RAIDZ3 + 2 hot spare) >> >> Regarding journal and scrubbing : by using ZFS i would think that i can >> safely not use the CEPH ones ... is this ok? >> >> Do you have some other advises and recommendations for me? (the >> read:writes ratios will be 10:1) >> >> Thank you!! >> Adrian >>
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