RankDisk records disk access events using the device drivers and bypasses the file system and the operating system's cache. This makes the measurement independent of the file system overhead or the current state of the operating system. In replaying traces, RankDisk always creates and operates on a new dummy file. This file is created in the same (or closest possible) physical location of the target hard disk. This allows the replaying of traces to be safe (does not destroy any existing files) and comparable across different systems. Due to the natural fragmentation of hard disks over time, they should be defragmented before running these tests.

The traces used for each test were created from real usage. The traces contain different amount of writing and reading on the disk; total ratio in the HDD test suite disk operations is 53% reads and 47% of writes.

The following input traces are used:

Windows XP Startup: This is the Windows XP start trace, which contains disk activities occurring at operating system start-up. The test is 90% reading and 10% writes. This trace contains no user activity.

Application Loading: This is a trace containing disk activities from loading various applications. It includes opening and closing of the following applications:

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

The application loading trace is 83% reads and 17% writes.

General Hard Disk Drive Usage: This trace contains disk activities from using several common applications.

These are:

Opening a Microsoft® Word document, performing grammar check, saving and closing        
Compression and decompression using Winzip        
Encrypting and decrypting a file using PowerCrypt        
Scanning files for viruses using F-Secure® Antivirus.        
Playing an MP3 file with Winamp        
Playing a WAV file with Winamp        
Playing a DivX video using DivX codec and Windows® Media Player        
Playing a WMV video file using Windows® Media Player        
Viewing pictures using Windows® Picture Viewer        
Browsing the internet using Microsoft® Internet Explorer        
Loading, playing and exiting a game using Ubisoft Tom Clancy's Ghost Recon

The General Usage trace is 60% reads and 40% writes.

Virus Scanning: Virus scanning is a critical task in today's PC usage. As the major bottleneck of scanning viruses is in hard disk activity, it is reasonable to include virus scanning as a HDD test. The test consists of HDD activity of scanning 600MB of files for viruses. The Virus Scanning test is mostly disk reading (99.5%).

File Write: This trace contains disk activities from writing 680MB files on the hard disk and no read operations are involved in this test.

PCMark replays a pre-recorded trace of IO back on the drive under test. This is one of the more real-world ways of testing, its weakness being that it is more of a short-term test and might not represent long-term usage of an SSD. We mitigate this somewhat by pre-conditioning the SSD prior to the test.