Thanks all I will probably have 2x10gb : 1x10gb for client and 1x10gb for cluster but I take in charge your recommendation Sebastien The 200GB SSD will probably give me around 500MB/s sequential bandwidth. So with only 2 SSD I can overload 1x 10gb network. Hum I will take care of osd density Sent from my iPhone > On 15 déc. 2014, at 21:45, Sebastien Han <sebastien.han@xxxxxxxxxxxx> wrote: > > Salut, > > The general recommended ratio (for me at least) is 3 journals per SSD. Using 200GB Intel DC S3700 is great. > If you’re going with a low perf scenario I don’t think you should bother buying SSD, just remove them from the picture and do 12 SATA 7.2K 4TB. > > For medium and medium ++ perf using a ratio 1:11 is way to high, the SSD will definitely be the bottleneck here. > Please also note that (bandwidth wise) with 22 drives you’re already hitting the theoretical limit of a 10Gbps network. (~50MB/s * 22 ~= 1.1Gbps). > You can theoretically up that value with LACP (depending on the xmit_hash_policy you’re using of course). > > Btw what’s the network? (since I’m only assuming here). > > >> On 15 Dec 2014, at 20:44, Florent MONTHEL <fmonthel@xxxxxxxxxxxxx> wrote: >> >> Hi, >> >> I’m buying several servers to test CEPH and I would like to configure journal on SSD drives (maybe it’s not necessary for all use cases) >> Could you help me to identify number of SSD I need (SSD are very expensive and GB price business case killer… ) ? I don’t want to experience SSD bottleneck (some abacus ?). >> I think I will be with below CONF 2 & 3 >> >> >> CONF 1 DELL 730XC "Low Perf": >> 10 SATA 7.2K 3.5 4TB + 2 SSD 2.5 » 200GB "intensive write" >> >> CONF 2 DELL 730XC « Medium Perf" : >> 22 SATA 7.2K 2.5 1TB + 2 SSD 2.5 » 200GB "intensive write" >> >> CONF 3 DELL 730XC « Medium Perf ++" : >> 22 SAS 10K 2.5 1TB + 2 SSD 2.5 » 200GB "intensive write" >> >> Thanks >> >> Florent Monthel >> >> >> >> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > > Cheers. > –––– > Sébastien Han > Cloud Architect > > "Always give 100%. Unless you're giving blood." > > Phone: +33 (0)1 49 70 99 72 > Mail: sebastien.han@xxxxxxxxxxxx > Address : 11 bis, rue Roquépine - 75008 Paris > Web : www.enovance.com - Twitter : @enovance > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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