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 [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
