Diskpar.exe: Disk Alignment Tool

DiskPar is a command-line tool that finds and modifies the starting sector on a disk to improve disk performance. It is only used with multi-disk systems.

Windows has an internal structure called the Master Boot Record (MBR) that limits the maximum default hidden sectors to 63. For this reason, the default starting sector for disks that report more than 63 sectors/track is the 64th sector. For disks with 64 or more sectors/track this can cause misalignment when data is transferred to and from the disks. For example, with a disk that has 64 sectors/track, what appear to be track aligned transfers begin at the last sector of one track and span to the next track. The following issues further complicate this problem:

• The track information reported by disks doesn't always reflect reality
• Many disks have different numbers of sectors on different tracks (for example: outer vs. inner bands)
• Basic Block Microsoft® MS-DOS® interoperability issues with Microsoft® Windows® 95 and Microsoft® Windows® 98 restrict changes to partition alignment

To get maximum disk performance on Windows for disks which have alignment optimizations and large track sizes, you can use DiskPar to obtain and set partition information. By doing so, you can significantly improve disk activity performance for some specialized controllers.

DiskPar Topics

• DiskPar Syntax
• DiskPar Example

File Required

• Diskpar.exe