Articles: Storage

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A hardware reviewer can be best characterized as “ever-searching”. He is constantly searching for new exciting devices to test as well as for new test methods that would reveal the capabilities of a particular device better. That’s why we added FC-Test to our synthetic benchmarks (IOMeter, WinBench, PCMark) to compare hard disk drives under real-life conditions. And now we want to compare HDDs using the defragmentation tool integrated into Windows XP. Why defragmentation? Because this application puts your hard disk under stress by copying large amounts of data. It ensures acceptable repeatability of results, yields visually comprehensible output and is employed by almost every PC user (we mean those users who care about how fast their PC is).

We also had to check out the influence of NCQ on the defragmentation speed after we had seen the results obtained by our colleagues. Their numbers were so shocking that we wanted to have them ourselves. :)

So, what is defragmentation, by the way? When saved to the hard disk, files are not always written into contiguous clusters. More often than not, they occupy a few strings of adjacent clusters in different parts of the platter. This occurs when a file stored on the hard disk gets larger after your processing it or when large files are written into an almost full hard disk or when there is no string of free adjacent clusters on the disk to save the current file. The oftener your files are modified, the more fragmented they come to be (i.e. a file is broken down into more fragments stored in different sections of the disk). As a consequence, the reading of the file takes longer since the HDD has to move its heads a longer way to collect the file fragments from the platters. The more fragmented your files are, the slower your PC works. Don’t you ever get annoyed at a game level or a heavy application (like Adobe Photoshop) loading up too slowly? You know the possible reason now.

So, file fragmentation is bad. It is an evil you have to fight. How? Programs called defragmenters are to be your main weapon. There are a lot of them available, but they all follow the same principle. The hard disk is analyzed to create a file distribution map. Then, fragmented files are moved into free disk space so that each file occupied adjacent clusters.

Defragmentation in Windows XP is supposed to be done with a standard integrated tool based on the commercial Diskeeper from Executive Software. Like most third-party defragmentation utilities, this program uses Microsoft’s API, the FSCTL command set (follow this link to learn more about it). As opposed to earlier implementations, e.g. in Windows NT and Windows 2000, the version integrated into Windows XP can defragment the Master File Table (MFT) and supports clusters larger than 4KB that are created when disk partitions larger than 4GB are formatted with the system default formatting tool. This application had proved so successful that it was transferred into Microsoft’s newest OS, Windows Vista, without modifications.

It is necessary to note, Microsoft recommends that you have at least 15% of free disk space on the disk volumes you want to defragment.

In this article we’ll see if defragmentation can be used as a performance test for hard disk drives. We will also see how the time it takes to perform a defragmentation procedure depends on the HDD’s support of Native Command Queuing technology.

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