MVP's Corner September 2007:

Measuring the Impact of File Fragmentation and Free Space Fragmentation on Drive Performance

Another of the questions that I am frequently asked is how to measure the impact of file fragmentation and free space fragmentation on drive performance.

 

Windows Performance Monitor provides some metrics that can indicate if fragmentation is a possible issue - including Disk Queue Length and Split I/O counts.  However, the information gathered and reported by Windows Performance Monitor is device specific.  It doesn't drill down to the actual file level.

 

This is where a tool like hIOmon (http://www.hyperio.com) comes in handy.  hIOmon provides very detailed performance information not only at the device level but also at the file level.  Information can be exported to a csv file which allows you to use Excel to do all sorts of fun things like graphing, pivot tables, etc…

 

I developed 2 scenarios for measuring the impact of fragmentation and free space fragmentation on drive performance.  Scenario 1 times how long it takes to read a file from beginning to end – once when the file is fragmented and again when the file is contiguous.  Scenario 2 measures both read and write performance when a drive has fragmented free space and again when the drive has consolidated free space. 

 

For Scenario 1, Raxco’s File Access Timer was used to read the fragmented/defragmented file from beginning to end.  hIOmon was used to gather detailed performance information for the fragmented/defragmented file.  From the comprehensive performance information that hIOmon provided, I compiled a short list of the most relevant metrics and explained what each metric means.

 

For Scenario 2, WinBench was used to perform standardized read/write activity and derive a drive performance score.  hIOmon was used to gather detailed performance information for the different drives.  From the comprehensive performance information that hIOmon provided, I’ve compiled a short list of the most relevant metrics and explained what each means.

 

For my detailed report on measuring the impact of file fragmentation and free space fragmentation on drive performance please click here.

 

Greg Hayes

Systems Engineer - Raxco Software

Microsoft MVP 2003-2007

Windows File Systems