The most accurate way to know how a device will perform and last in a given usage environment is to perform a field test. The goal of the field test is to collect real usage data and then, using some basic performance information you will also collect, apply this data into a spread sheet that will help you estimate how long a device will last in your specific usage environment. Again, this is necessary because of the unique pattern of usage determined by the way your storage device, system, and usage environment interact. Every flash device will have its own unique pattern of usage.
Please note, determining how long a device will last in your application is somewhat involved but we have broken the entire process into simplified steps to curb the complexity. The field test steps are Gather Usage Data, Input Usage Data, and Determine File Size IOPS. Simply follow the outlined process below to estimate the useful life of a device in your application.
To gather the usage data, we recommend an application called DiskMon, which is a Windows application that logs and displays all drive activity. By enabling this application while your device is experiencing real-life activity, you will be able to determine a realistic usage model for your system and in combination with our Drive Life Spreadsheet (step 3), you will gain insight into usage data such as average file size, percentage of reads/writes, percentage of random/sequential, amount of data being written and dozens of other valuable usage figures.
To perform a successful test, you will need to configure your device and replicate the computing activity it will endure over its lifetime for a sample time period. The best way to replicate the type of usage it will endure is to put the device into service in the actual computing environment for which it is being tested. On average, we suggest the field test last one week so that enough transfer activity can take place on the device.
DiskMon runs on Widows XP and higher for client operating systems and Windows Server 2003 and higher for server operating systems. Unfortunately, a comparable application is not currently available for Linux users.
A - Download and install the DiskMon application into the system.
B - Ensure that DiskMon is properly configured and running on your system before deploying into the field for data gathering. You can do this by running the application for a 5 minute test and verifying data is being collected.
C - Deploy the system into the field application for a period of time that will allow it to adequately perform routine transfer activity. The goal is to have the drive take on wear and tear that is akin to what it will experience throughout its useful life.
D - Important: When you have completed gathering usage data at the end of your test period, be sure to save the usage data before closing the program as DiskMon does not automatically save the data. You will need this information in the next step.
In this step we need to gather the Average Write File Size for your application as well as the Percentage Random/Sequential Distribution. To do this you need to input the usage data collected during your field test into the Drive Life Spreadsheet (download above). All the necessary instructions for inputing your data are included at the top of the Drive Life Spreadsheet. Please be sure to save a copy of this spreasheet for usage throughout the field test.
At this point you have input your usage data into the Drive Life Spreadsheet to find out out what your Average Write File Size and Percentage Random/Sequential Distribution are. In this final step you will run a test to find out how the IOPS performance of your storage device operates in your particular usage environment. With this data you can successfully estimate your drive's useful life. To run the IOPS test, you will simply need to install the IOmeter Test Package (download above) into the actual system that is being tested, configure two settings, and run the test. The process of capturing this data is as follows:
A - Download the IOmeter Test Package (above).
B - Double-click the file named "Write IOPS Test" to start IOmeter.
C - Click the "+" on your computer name.
D - Click on "Worker 1" and then select the drive you want to test.
E - Next we have to tailor this test to include the Average Write File Size and Percentage Random/Sequential Distribution gathered from the Drive Life Spreadsheet. To configure this test, first click on the "Access Specifications" tab, then the "Write IOPS Test" on the right, and finally on the "Edit" button.
F - In this dialog we customize the test to the results from your field test. First, set the “Transfer Request Size” to be the Average Write File Size reported on the Drive Life Spreadsheet. Then you must also set the “Percent Random/Sequential Distribution” to match the results reported Drive Life Spreadsheet.
G - Start the test by pressing the green flag button.
H - With the test complete, your IOPS figure will be displayed on the Results Display tab under Total I/Os per Second. You will need this figure for the next step.
Final Step: Now that you have the storage device's IOPS speed for the average file size in your particular usage environment, we can input this data into the Drive Life Spreadsheet and find out the estimated useful life. Please note, this must be the same Drive Life Spreadsheet that has the original usage data collected at the beginning of this field test.