On Wed, Feb 20, 2013 at 10:36 AM, Mark Nelson <mark.nelson@xxxxxxxxxxx> wrote: > Hi Jonathan, > > > On 02/20/2013 12:28 PM, Jonathan Rudenberg wrote: >> >> I'm currently planning a CEPH deployment, and we're looking at 36x4TB >> drives per node. It seems like the recommended setup is an OSD per drive, is >> this accurate? What is the recommended ratio of drives/OSDs per CPU core? >> Would 12 cores be enough (3:1 ratio)? > > > Typically 1 drive per OSD is the way to go, but once you get up into the 36+ > drives per node range there start becoming trade-offs (especially with > things like memory usage during recovery, etc). You may need to do some > testing to make sure that you don't end up hitting swap. > > I've got a SC847a chassis we are using for testing at Inktank with 36 bays. > I'm using dual E5-2630ls and that seems to be working pretty well, but I > wouldn't go any slower than those chips. E5-2630s or 2640s might be a bit > better, but so far it looks like ivy bridge is fast enough that you can > fudge a bit on our "1ghz of CPU per OSD" guideline and get a pair of the > cheaper 6-core chips. That 1GHz per daemon recommendation is based on recovery performance; in general usage it'll often be much lower. I don't think you've done much with recovery yet, so don't count on that ratio working out once you do so! -Greg _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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