Simple RAID Calculator

by Paul on November 28, 2011

I mentioned in my previous post that I’m presenting at the inaugural PING Philly meetup and my topic is on sizing and configuring backend storage. One of the main points I want to stress in my discussion is the importance that IOPS have when planning your storage configuration. To help illustrate this importance, I created a simple RAID group calculator that shows an estimate of the total backend IOPS required to satisfy your application’s performance needs. Here’s the link to the calculator:


Another thing to note is that this calculator is my first javascript project. Thanks to the incredible teaching skills (and infinite patience) of @jpirrello, I was able to complete this calculator in about a day’s worth of time. The calculator has a slight bias towards EMC hardware – specifically the disks. (Sorry NetApp, I still think you’re cool though!) As of now, the disk sizes don’t play any role in the calculator. That will be in the next version :) I also made some assumptions on the total IOPS per disk. Here’s the break down:

SSD = ~5250 IOPS
15K = ~175 IOPS
10K = ~135 IOPS
7.2K = ~75 IOPS

These estimates are the average of a variety of drives I’ve found on the interent. I also compared them to this:

I’d like to add more functionality to the calculator, so feel free to add comments below with your thoughts and suggestions for how I can improve it!


  • Christopher K. Nickl

    I completely understand your point and agree, for the most part.  However IOPS is a loaded number.  There are a LOT of factors that go into that number, specificly block size, as well as the size of the data being read/written.  I’ve done a lot of work soley with IOPS only to have that number not work because the IOPS calculation was done based on a standard block size, and yet the real-world data performed completely differently.

    That being said i have SSDs that will blow that 5200 IOPS away, it’s all about manipulation.  You can make any disk give a VERY large range of IOPS numbers.  I can make a 7.2k SATA look very good vs a SAS disk.

  • Boris Pavlik

    Agree with Christopher, so adding these few things could really help for better estimation…

Previous post:

Next post: