Remarks on Windows Disk and File IO During System Boot

Performance/Sizing, Windows Internals
Published Jul 10, 2013

Let use take a look at some graphs I created with Windows Performance Analyzer (WPA), showing a typical corporate laptop boot Windows 7. Detailed information on creating such a trace can be found in my earlier article Analyzing a Slow Boot with Windows Performance Recorder & Analyzer.

Disk and File IO during Windows 7 boot - Windows Performance Analyzer

Analysis

Several things can be learned analyzing the graphs:

IO count and IOPS are much higher when measured at application level (top graph) versus at disk level (bottom graph) - notice the different scaling of the y-axis! See my earlier article The Impossibility of Measuring IOPS (Correctly) for more information on this topic.
Contrary to popular belief the boot phase IO pattern shows not only reads, but a substantial amount of writes, too: 16% in this case. I am sorry about the colors, by the way. I tried but could not get WPA to change the colors so that reads and writes look less similar.
Windows’ boot phase obviously is very IO intensive. In this case we have a total of 62,000 IOs over a time period of 330 seconds which amounts to 188 IOPS on average. That is not bad for a poor magnetic hard drive at all, but this system would benefit greatly from an SSD.

Bonus takeaway: IOPS are a function not only of the drive speed but also of the application(s) generating the IOs.

Boot IOPS Windows Performance Toolkit (WPT)

Comments

Comments are powered by Giscus. Please enable JavaScript to view them, or view discussions directly on GitHub.

Related Posts

Performance Impact of Windows Offline Files

A little known fact about the Windows Offline Files functionality is it slows down network operations considerably. Here is how and why. Test Results The following tests were performed with a set of 1,114 files of a total size of 408 MB. In the copy test the files were copied from a Windows 7 client machine to a file server over a 100 MBit LAN connection. In the delete test the files were deleted on the file server. No antivirus or other security products were running on either side. Each test was run twice, the table lists the average.

Boot IO Analysis with uberAgent for Splunk 1.5

Boot IO Analysis with uberAgent for Splunk 1.5

Analyzing slow boots is a difficult task. You need to install software like XPerf and master its far-from-intuitive command-line options to generate a trace file that you can then analyze. Once you find a possible cause for the long startup duration you never know if it is specific to the machine you analyzed or if it affects other PCs, too. In other words: XPerf, although powerful, is difficult to master. And it does not scale. uberAgent does. And it is super-easy to use.

Benchmarking a $11,699 HP Enterprise Performance SSD

Benchmarking a $11,699 HP Enterprise Performance SSD

[Update on 29/06/2012: added tests 5 and 6 with RAID controller cache and Atlantis Ilio] When a 400 GB SSD comes nearly at the price of a small car, you expect a lot, performance-wise. At least I did when I got my hands on two drives from HP’s enterprise performance series. Read on to find out if that hefty price tag is justified.

Performance/Sizing

The Impossibility of Measuring IOPS (Correctly)

The Impossibility of Measuring IOPS (Correctly)

If you have ever used Sysinternals’ Process Monitor, chances are high you were a little intimidated when you looked at your first capture: it probably contained hundreds of thousands of registry and file system events, generated in a minute or less. That amount of activity must surely indicate high system load - but strangely, very often it does not. Looking at the hard disk LED you will only see an occasional flickering, even though thousands of file system events are captured per second. How is that possible? Read on to find out.

Performance/Sizing

Latest Posts

WSL Disk Space Cleanup

WSL Disk Space Cleanup

The Windows Subsystem for Linux (WSL) stores its virtual hard disks in the user profile on drive C:. These VHDX files can grow up to 1 TB in size, making it necessary to clean up and reclaim space occasionally. This article shows how.

Virtualization & Containers

Changing the Location of PowerShell Profile Scripts

A PowerShell profile is an init script that is executed when the shell starts. PowerShell searches for profile scripts in hard-coded locations. This article explains how to move profile scripts to any directory of your choice.

Changing the Location of the Windows Terminal Settings Files

Changing the Location of the Windows Terminal Settings Files

Windows Terminal stores its settings in configuration files that resides in the Windows user profile. This article explains how to move them to any directory of your choice. Where are the Settings Files Located? The location of the Windows Terminal settings file is hard-coded. The exact path depends on the app variant you installed, but it’s always in the user profile:

Fast & Silent 5 Watt PC: Minimizing Idle Power Usage

Fast & Silent 5 Watt PC: Minimizing Idle Power Usage

This micro-series explains how to turn the Lenovo ThinkCentre M90t Gen 6 into a smart workstation that consumes only 5 Watts when idle but reaches top Cinebench scores while staying almost imperceptibly silent. In the first post, I showed how to silence the machine by replacing and adding to Lenovo’s CPU cooler. In this second post, I’m listing the exact configuration that achieves the lofty goal of combining minimal idle power consumption with top Cinebench scores.