Every HDD has a “mean access time” number (related to the rotation speed, number of heads, etc.) with 8ms access time this gives you 1000/8 = 125 seeks per second.
This is where it comes from :-) Of course the best case will be better, I generally calculate 150 IOPS for any SATA drive, 200 for SAS. Some high-end FC disks with 15K RPM can have as high as 300 IOPS, but that’s probably not what we want to use here. Jan > On 02 Jul 2015, at 17:53, Steffen Tilsch <[email protected]> wrote: > > Hello Cephers, > > Whenever I read about HDDs for OSDs it is told that "they will deliver around > 130 IOPS". > Where does this number come from and how it was measured (random/seq, how big > where the IOs, which queue-dephat what latency) or is it more a general > number depending on disk seek times? > > Regards and thanks for clarifying, > Steffen > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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