Mark Nelson wrote: > I'm not sure who came up with the 1GB for each 1TB of OSD daemons rule, but frankly I don't think it scales well at the extremes. You can't get by with 256MB of ram for OSDs backed by 256GB SSDs, nor do you need 6GB of ram per OSD for 6TB spinning disks. > > 2-4GB of RAM per OSD is reasonable depending on how much page cache you need. I wouldn't stray outside of that range myself. Ok. It's recorded. > What it really comes down to is that your CPU needs to be fast enough to process your workload. Small IOs tend to be more CPU intensive than large IOs. Some processors have higher IPC than others so it's all just kind of a vague guessing game. With modern Intel XEON processors, 1GHz of 1 core is a good general estimate. If you are doing lots of small IO with SSD backed OSDs you may need more. If you are doing high performance erasure coding you may need more. If you have slow disks with journals on disk, 3x replication, and a mostly read workload, you may be able to get away with less. > > As always, the recommendations above are just recommendations. It's best if you can test yourself. Yes, sure. Thx for the explanations Mark. :) Bye. -- François Lafont _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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