FAQ - Measuring performance with IOMeter

Below are step I do to setup IOMeter. After you get an understanding of all the settings you can adjust them to test a specific test case you are interested in. If anyone has any questions just let us know.


1. Download IOMeter and install it (you can download it at http://www.iometer.org ).

2. Before I launch IOMeter I create a network drive that is mapped to the NAS share I want. Whatever drive letter you assign to your network drive write it down you will need it later.

3. The next step is to launch IOMeter.

4. When IOMeter is up and running go to the “Topology” field and select your PC name and when the tree expands select “Worker 1”.

5. The “Disk Targets” tab should be selected by default and it should show you all the drives that are available to IOMeter. Select your mapped drive.

6. Then you must enter in a value where it says “Maximum Disk Size”. I enter in 2048000 sectors. What IOMeter does here is create a file it calls “iobw.tst” in your share and the runs test using that file size. I purposely use a 1gig file because I want to make sure that the test is forced to write and read to disk with out the possibility of the test just using the NAS memory and not the disks.

7. The next step is to create the test scripts you will be using. I set my up as follows. Select the “Access Specifications” tab. Then click on the “New” button.

A new popup shows up that allows you to set your access specs. Set only the following:

Transfer Request Size = 256 Kilobytes
Percent Random/Sequential Distribution = 100% Sequential
Percent Read/Write Distribution = 100% Write

All the other options you don’t need to touch. Under the name file I enter in 256K_Write. Select OK. If you scroll down the “Global Access Specifications” field you will see your newly created test script. Select the new script and click on the “add” button. The script I just did is only for Writes and you will need repeat the step you just did but in the “Percent Random/Write Dist” you set it to 100% read and finally I name my test script 256K_Read. After you select the Read script you are done with this tab.

Alternatively, you can right-click and save the IOMeter config file iometer.icf, and load it in IOMeter.

8. Select the “Results Display” tab. Then change the “Update Frequency” to 1.

9. Now select the “Test Setup” tab. Modify the “Run Time field to 2 minutes.

10. There is an icon that looks like a floppy disk click on it. Save your file with whatever name you want.

11. Click on the green flag icon and your tests are off and running.


You now have your test scripts ready. When you first run your tests you will notice in the “Results Display” tab that nothing is happening. This is because IOMeter is creating the test file on your network drive.


For general reference here is our hardware configuration we use for testing performance.

Computer: 2.60GHz, 1 GB of RAM, Seagate St380023AS 80GB drive, Intel Pro/1000 CT Nic.

Software: Win2k Service Pack 4

Switch: SMC 8508T