El 06/05/14 17:51, Wido den Hollander escribi?: > On 05/06/2014 05:07 PM, Xabier Elkano wrote: >> >> Hi, >> >> I'm designing a new ceph pool with new hardware and I would like to >> receive some suggestion. >> I want to use a replica count of 3 in the pool and the idea is to buy 3 >> new servers with a 10-drive 2,5" chassis each and 2 10Gbps nics. I have >> in mind two configurations: >> > > Why 3 machines? That's something I would not recommend. If you want 30 > drives I'd say, go for 8 machines with 4 drives each. > > If a single machine fails it's 12.5% of the cluster size instead of 33%! > > I always advise that a failure of a single machine should be 10% or > less of the total cluster size. > > Wido The idea is to start with 3 nodes and scale them in the future. I am aware that a server failure can be 33% less performance, but if the whole pool performance is good enough with 3 replicas spread over 3 nodes, maybe it could coupe with that. The biggest cost here is the racks and servers, instead of the disks, and I prefer start with 3 high density servers and scale up them progressively. Do you think that this cannot good enough for production? > >> 1- With journal in SSDs >> >> OS: 2xSSD intel SC3500 100G Raid 1 >> Journal: 2xSSD intel SC3700 100G, 3 journal for each SSD >> OSD: 6 SAS10K 900G (SAS2 6Gbps), each running an OSD process. Total size >> for OSDs: 5,4TB >> >> 2- With journal in a partition in the spinners. >> >> OS: 2xSSD intel SC3500 100G Raid 1 >> OSD+journal: 8 SAS15K 600G (SAS3 12Gbps), each runing an OSD process and >> its journal. Total size for OSDs: 3,6TB >> >> The budget in both configuration is similar, but the total capacity not. >> What would be the best configuration from the point of view of >> performance? In the second configuration I know the controller write >> back cache could be very critical, the servers has a LSI 3108 controller >> with 2GB Cache. I have to plan this storage as a KVM image backend and >> the goal is the performance over the capacity. >> >> On the other hand, with these new hardware, what would be the best >> choice: create a new pool in an existing cluster or create a complete >> new cluster? Are there any advantages in creating and maintaining an >> isolated new cluster? >> >> thanks in advance, >> Xabier >> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users at lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > >
 |