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A question often asked is how to calculate IOps. Every disk in your storage system has a maximum theoretical IOps value that is based on a formula.
Disk performance and IOps is based on three key factors:
- Rotational speed. Measured in RPM, mostly 7,200, 10,000 or 15,000 RPM. A higher rotational speed is associated with a higher performing disk.
- Average latency. The time it takes for the sector of the disk being accessed to rotate into position under a read/write head.
- Average seek time. The time (in ms) it takes for the hard drive’s read/write head to position itself over the track being read or written.
Average IOPS: Divide 1 by the sum of the average latency in ms and the average seek time in ms (1 / (average latency in ms + average seek time in ms).
I usually use a standard average IOps of a drive based on their rotation speed
RAID introduces a write penalty
The question of course is how many IOps do you need per volume and how many disks should this volume contain to meet the requirements?
Write IOPS for a 15k disk
Use this RAID_spindle_calculator to calculate the IOPS your new raid set can deliver.