Hello, On Wed, 01 Oct 2014 18:26:53 +0200 Massimiliano Cuttini wrote:
> Dear all, > > i need few tips about Ceph best solution for driver controller. > I'm getting confused about IT mode, RAID and JBoD. > I read many posts about don't go for RAID but use instead a JBoD > configuration. > > I have 2 storage alternatives right now in my mind: > > *SuperStorage Server 2027R-E1CR24L* > which use SAS3 via LSI 3008 AOC; IT Mode/Pass-through > http://www.supermicro.nl/products/system/2U/2027/SSG-2027R-E1CR24L.cfm > > and > > *SuperStorage Server 2027R-E1CR24N* > which use SAS3 via LSI 3108 SAS3 AOC (in RAID mode?) > http://www.supermicro.nl/products/system/2U/2027/SSG-2027R-E1CR24N.cfm > Firstly, both of these use an expander backplane. So if you're planning on putting SSDs in there (even if just like 6 for journals) you may be hampered by that. The Supermicro homepage is vague as usual and the manual doesn't actually have a section for that backplane. I guess it will be a 4link connection, so 4x12Gb/s aka 4.8 GB/s. If the disks all going to be HDDs you're OK, but keep that bit in mind. > Ok both of them solution should support JBoD. > However I read that only a LSI with HBA or/and flashed in IT MODE allow > to: > > * "plug&play" a new driver and see it already on a linux distribution > (without recheck disks) > * see S.M.A.R.T. data (because there is no volume layer between > motherboard and disks) smartctl can handle handle the LSI RAID stuff fine. > * reduce the disk latency > Not sure about that, depending on the actual RAID and configuration any cache of the RAID subsystem might get used, so improving things. The most important reason to use IT for me would be in conjunction with SSDs, none of the RAIDs I'm aware allow for TRIM/DISCARD. to work. > Then i should probably avoid LSI 3108 (which have a RAID config by > default) and go for the LSI 3008 (already flashed in IT mode). > Of the 2 I would pick the IT mode one for a "classic" Ceph deployment. > Is it so or I'm completly wasting my time on useless specs? > It might be a good idea to tell us what your actual plans are. As in, how many nodes (these are quite dense ones with 24 drives!), how much storage in total, what kind of use pattern, clients. Regards, Christian > > Did I getting the point? What would you reccomend? > I'm getting dumb reading by myself tons of specs without any second > human opinion. > > Thanks you for any hint you'll give! > -- Christian Balzer Network/Systems Engineer ch...@gol.com Global OnLine Japan/Fusion Communications http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
