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Moreover, the trace should contain not only the requests sent by user programs to the HDD, but the entire disk activity of the operation system (swap-file requests, keeping transaction logs, etc.). So, I would take the phrase “file is created in the same (or closest possible) physical location of the target hard disk” with a grain of skepticism.

Of course, I do understand the desire of PCMark04 developers to let not only professionals, but also the regular users to test their hard disk drives. However, when you are testing a HDD with the already installed OS, you automatically break the major requirement to the testing environment: you will not get repeated results, as the tested drive is not free from the influence of the operation system.

Luckily, PCMark04 also allows running the tests on a non-formatted HDD:

Well, I believe this screenshot could scare an unprepared user :)

So, PCMark04 reproduces the following types of disk workload:

Windows XP Startup: This trace contains a sequence of requests sent to the HDD on system start-up.

Application Loading: This trace contains disk activity when the system opens and closes the following applications:

  • Microsoft Word
  • Adobe Acrobat Reader 5
  • Windows Media Player
  • 3DMark 2001SE
  • Leadtek Winfast DVD
  • Mozilla Internet Browser

File Copying: This trace contains a log for HDD requests recorded during the copy of about 400MB of files. Unfortunately, there is no mention of the average file size or of the number of files in the given PDF-file.

General Hard Disk Drive Usage: This trace contains the info about disk activity during the work of some widely spread applications. When we recorded this trace the following things were undertaken:

  • We opened a Microsoft Word document, checked the grammar, saved and closer the file.
  • With WinZIP utility the file was packed and then unpacked.
  • The file was encoded and then decoded with PowerCrypt utility.
  • A set of files was checked for viruses with F-Secure Antivirus software.
  • WinAmp played MP3- and WAV-files.
  • Windows Media Player played DivX-video.
  • The system browsed through the pictures with Windows Picture Viewer .
  • Etc.

To reduce the time required to process a single trace, we compressed the latter: the long pauses between requests were reduced to 50milliseconds. This value was derived experimentally and represents the minimal pause possible without affecting the disk subsystem performance.

Having run all the tests for a given HDD, PCMark04 generates a certain performance index calculated according to the following formula:

HDD Score = (XP Startup Trace x 120) + (Application Load trace x 180) + (File Copy Trace x 28) + (General Usage x 265)

This sophisticated rating formula can actually be explained in a very simple way. The results of the subtests weight differently in the end. For instance, the Windows loading speed weighs 25%, while the applications loading weighs a little bit more: 28%. Copy speed on the contrary weighs less – 12% only. And finally the maximum weight of 35% belongs to the general hard Disk Drive Usage.

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