Re: IOPS and megacycles calculations

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Hi John

Working away frantically here .. let you know my update in a bit but I need
to know something where are you getting this information from?

" If I take a 15K FC SCSI spindle for example, I get 130 IOPS at
20ms and over 200 IOPS at 60ms. When the spindles get overloaded to a point
(about 400 IOPS for our example 15K FC spindle) the IOPS/spindle doesn't go
up any more and the response time gets longer and longer as the load
increases."

How do u know this?

Also

"(1,500 × 2/3) + ((1,500 × 1/3) × 2) = 2,000

Applying the same scenario on a RAID-5 array, your actual hardware IOPS is:

(1,500 × 2/3) + ((1,500 × 1/3) × 4) = 3,000

If all of your drives are 10,000 RPM, you will need at least 30 drives to
obtain your required IOPS in a RAID-5 configuration. If you implement RAID-1
or RAID-10 instead, then you would need at least 20 drives (you can't have a
RAID-1 or RAID-10 solution with an odd number of disks)."


How are you (or they) working out these values?

I have a gap here in my knowledge that I need to address to understand
things further on!!


Tony

.

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