À : ceph-users@xxxxxxxxxxxxxx Objet : Re: Ceph / Dell hardware recommendation On 01/15/2014 08:29 AM, Derek Yarnell wrote: > On 1/15/14, 9:20 AM, Mark Nelson wrote: >> I guess I'd probably look at the R520 in an 8 bay configuration with >> an >> E5-2407 and 4 1TB data disks per chassis (along with whatever OS disk >> setup you want). That gives you 4 PCIE slots for the extra network >> cards, the option for a hardware raid controller, and some expansion >> options if you want to add more disks. It's not the densest chassis >> and I've never tested performance on it, but it's a fairly >> straightforward setup with no expanders to worry about and a cheap/fast CPU. > > Dell recently will sell now a R720xd with a pure LSI card in it (you > will need to ask). This is important that the PERC controllers do not > support JBOD mode and really for Ceph you don't want a hardware raid > controller. They currently give me a hard time about trying to mix > and match SSDs though on the 12 bay back-plane which is not a > technical problem but a Dell problem. However you can get two flex > bays in it which they allow you to put SSDs in. So you can get 12 4TB > drives and 2 100G eMLC drives in 2U. That's good to know that they will sell LSI controllers in the R series now! JBOD vs RAID has some nuances. As far as I know, LSI controllers basically disable cache when put in JBOD mode (as opposed to something like Areca that keeps it enabled), so you give up a lot when you run in JBOD mode. With SSD journals (that have a supercap) this is much less of an issue as you don't have to worry about journal writes and data writes competing on the same disk. With journals on disk, it appears that controllers with WB cache can help quite a bit. In this scenario you'd use single disk RAID0 arrays. This is actually what DreamHost does. Thank you all for comments, So to sum up a bit, it's a reasonable compromise to buy : 2 x R720 with 2x Intel E5-2660v2, 2.2GHz, 25M Cache, 48Gb RAM, 2 x 146GB, SAS 6Gbps, 2.5-in, 15K RPM Hard Drive (Hot-plug) Flex Bay for OS and 24 x 1.2TB, SAS 6Gbps, 2.5in, 10K RPM Hard Drive for OSDs (journal located on each osd) and PERC H710p Integrated RAID Controller, 1GB NV Cache ? Or is it a better idea to buy 4 servers less powerful instead of 2 ? > > Thanks, > derek > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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