Hi, maybe it can help, I'm doing same tests that stefan, random write with 4K with 3 nodes with 5 osds (with 15K drives) fio --filename=[disk] --direct=1 --rw=randwrite --bs=4k --size=100M --numjobs=50 --runtime=30 --group_reporting --name=file1 I can achieve 5500io/s (disks are not at 100%) cpu is around 30%idle ( 8 cores E5420 @ 2.50GHz) ----- Mail original ----- De: "Mark Nelson" <mark.nelson@xxxxxxxxxxx> À: "Stefan Priebe - Profihost AG" <s.priebe@xxxxxxxxxxxx> Cc: "Gregory Farnum" <greg@xxxxxxxxxxx>, ceph-devel@xxxxxxxxxxxxxxx Envoyé: Jeudi 28 Juin 2012 16:38:32 Objet: Re: OSD Hardware questions On 06/28/2012 08:21 AM, Stefan Priebe - Profihost AG wrote: > Am 27.06.2012 18:00, schrieb Mark Nelson: >> On 06/27/2012 10:28 AM, Stefan Priebe wrote: >>>> Well, as we said, 1GHz/OSD was a WAG (wild-ass guess), but 3.6GHz+/OSD >>>> is farther outside of that range than I would have expected. It might >>>> just be a consequence of using SSDs, since they can sustain so much >>>> more >>>> throughput. >>> >>> Sure it was just so much away from 1Ghz that i wanted to ask. >>> >>>> What is the cluster doing when you see those CPU usage numbers? >>> random write I/O from one KVM. 14k I/Ops with random 4k writes. >>> >>> Stefan >> >> I think I was seeing about 80-85% CPU utilization with 5 SSD OSDs on our >> 6-core AMD nodes, but I was just doing sequential writes with rados >> bench. > > While doing sequential writes i see pretty low CPU usage. Random writes > is the problem. > > Stefan It would be interesting to see where all your CPU time is being spent. What benchmark are you using to do the random writes? Mark -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- -- Alexandre D e rumier Ingénieur Systèmes et Réseaux Fixe : 03 20 68 88 85 Fax : 03 20 68 90 88 45 Bvd du Général Leclerc 59100 Roubaix 12 rue Marivaux 75002 Paris -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
