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How to calculate IOPS

post #1 of 3
Thread Starter 
Hey guys,

So I have been trying to figure out how to calculate IOPS for SSDs, both in RAID and Non-RAID setups.

So I know to calculate IOPS for standard rotational drives it follows this type of formula, albeit an approximate.
ALS = Average Latency in Seconds
= 30 / (Drives RPM)


ASTS = Average Seek Time in Seconds
This calculation however isn't as simple.
Go here to look at some details


IOPS = Input/Output Operations Per Second = 1/(ALS+ASTS)

Example:
RPM of Drivee: 10,000
Average latency: 3 ms (0.003 seconds)
Average seek time: 4.2 (r)/4.7 (w) = 4.45 ms (0.0045 seconds)
Calculated IOPS for this disk: 1/(0.003 + 0.0045) = about 133 IOPS


But pretty much ALL of that is irrelevant to SSDs. So how to you go about calculating IOPS for SSDs?

What about for RAID setups?
 
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Play Server
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post #2 of 3
With SSDs i think you have to benchmark them or look at the documentation to get the IOPs value. I may be wrong but as far as i know thats how you can get the values for an SSD.

You could also look up the average latency values for a particular SSD and plug em in and maybe that would work, but expect to be working with some very small numbers (on the order of several nanoseconds)
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post #3 of 3
Thread Starter 
Yeah, I would imagine the formula would remain the same. I guess I was more interesting in how RAID worked it's way into the equation, as far as, I know the individual drive specs, what happens if I combine those drives in RAID 0, 1, 5, 10, etc.

I know it's not linear in the sense if two drives have IOPS of 10,000....that doesn't necessarily mean you have 20,000 when in raid 0 for example.

I know how I can compare writes and reads and the differences when raided, at least to a certain degree....but not sure how to tackle IOPs for raided systems.
 
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12x 4TB HGST 5K4000 SanDisk SSD 960GB (cache) 6x 8TB WD Red Scythe AP-29 
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Play Server
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CPUCPUMotherboardRAM
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Intel X25-M G2 80GB Redundant 840W PSU Dell 710 2.5" - Google Search Appliance Dell Perc H700 Raid Controller 
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Intel Xeon E5-2670 v1 Intel Xeon E5-2670 v1 SuperMicro X9DRL-iF 64GB Kingston ECC (kvr16r11d4/16HA) 
Hard DriveHard DriveHard DriveCooling
12x 4TB HGST 5K4000 SanDisk SSD 960GB (cache) 6x 8TB WD Red Scythe AP-29 
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2x Noctua U9DXi4 FreeNAS Corsair AX750 Norco RPC-4224 
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