Benchmarking your Disk I/O

Posted on 4 mins read

How fast is your storage? How do you even check what kind of throughput you are getting?

That is a question that comes up often enough, when performing benchmarks.

I actually dealt with such a case last week. The customer was performing a storage Migration of all their VM’s from an HP MSA Array to a NetApp Filer. In order to ensure that no decrease in performance was experienced, I needed to benchmark the the disk I/O before and after the migration.

There is an “unofficial storage performance thread”  which is on the VMTN forums. This is actually an follow up on a even older thread that started way back in February 2007.

The principle is the same.

  1. Prepare a Windows VM. This VM does not need anything specific in it, so a basic install will do just fine.

  2. Add a Second Disk to the VM (10GB will do fine)

  3. Format the new Drive with NTFS.

  4. Download Iometer - according  to your operating system (32/64 bit)

  5. Download the Unofficial performance config test file

  6. Extract the zip file. Copy the Dynamo.exe and IOmeter.exe files (located under the .\iometer-2008-06-22-rc2.win.32\iometer-2008-06-22-rc2\src\Release folder) to your VM

  7. Copy the OpenPerformanceTest.icf file you downloaded in Step 5 to the VM.

  8. Double click on the IOmeter file.

  9. You will be presented with a window like this below

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  10. Click on the folder icon to load the config file for the test and point it to the OpenPerformanceTest.icf

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  11. Choose your newly created drive that formatted in Step 3

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  12. Click the Access Specifications Tab and add the bottom four tests to the Assigned Access Specifications

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    You can if you would like click on edit to see what each of these specifications will test - and customize to your liking if need be.

  13. Click the green flag to start the test.

  14. You will be asked for the to save the file.

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  15. IOmeter will then begin to prepare the drive.

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    What does that mean. IOmeter will create a file in the root of the drive you selected (approximately
    4 GB, that is why 10GB is more than enough, and then perform the tests on that file).

    This can take a while but let the process run.

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  16. Once the preparation is complete the tests will run, each test for 5 minutes. During that time you can see the real-time results by choosing the results Display tab

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  17. You can see which test is currently running at that time by clicking the Access Specifications Tab

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  18. Once the tests are finished (20 minutes) you will be presented with a CSV file.

  19. Open that file in Excel.
    The interesting columns that you would like to use (if you want to compare to others in the thread) are:
    G, J, O and AT (IOps, MBps, Ave Response Time, % CPU Utilization)

    • IOps - The Average # of IOps achieved / sec
    • MBps - Throughput in MBps
    • Ave. Response Time - Average response time in ms
    • % CPU Utilization - How much of the vCPU was utilized in %.

  20. I usually run the test 3 times - and collect the average of the three.

  21. The next time you run the test - you will not have to wait to prepare the drives be cause the file is already there.

  22. To clear the results click on reset workers button

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  23. Start again at Step 9.

Share your findings with others in the community by posting your results to the
unofficial storage performance thread

Update(25-Jun-10): As a result of he discussions based on the comments of this post and with the generous help of Didier Pironet of DeinosCloud - I am adding below a more “real-life” configuration test file for IOmeter.

Didier prepared this Config file according to HOWTO - Benchmark an iSCSI target (and any block target, including within VMs living in NFS datastores) from Chad Sakacc.

IOmeter Benchmark

The specs are pretty clear and divided in 4 groups: Regular NTFS, Exchange, SQL and backup/restore

4K; 100% Read; 0% random (Regular NTFS Workload 1)  
4K; 75% Read; 0% random (Regular NTFS Workload 2)  
4K; 50% Read; 0% random (Regular NTFS Workload 3)  
4K; 25% Read; 0% random (Regular NTFS Workload 4)  
4K; 0% Read; 0% random (Regular NTFS Workload 5)  
  
8K; 100% Read; 0% random (Exchange Workload 1)  
8K; 75% Read; 0% random (Exchange Workload 2)  
8K; 50% Read; 0% random (Exchange Workload 3)  
8K; 25% Read; 0% random (Exchange Workload 4)  
8K; 0% Read; 0% random (Exchange Workload 5)  
8K; 50% Read; 50% random (Exchange Workload 6)  
  
64K; 100% Read; 100% sequential (SQL Workload 1)  
64K; 100% Write: 100% sequential (SQL Workload 2)  
64K; 100% Read; 100% Random (SQL Workload 3)  
64K; 100% Write: 100% Random (SQL Workload 4)  
  
256K; 100% Read; 100% sequential (Backup)  
256K; 100% Write100% sequential (Restore)

Those two specs below don’t mimic any Operating Systems/Applications behavior. It just tells you the maximum IOPS the storage can supply.

512B: 100% Read: 0% random (Max Read IOPS)  
512B: 100% Write: 0% random (Max Write IOPS)