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Two utilities, Diskpart or Diskpar, can improve hard disk performance by as much as 20% by aligning the partition tracks with the disk tracks. This is especially important for applications such as Microsoft Exchange, which have highly random I/O.
Diskpart (note the final "t") comes with Windows Server 2003. Diskpar is an older version that comes with Windows 2000. Both of them do the same job in pretty much the same way.
The reason these utilities can improve performance is that Windows allows as many as 63 hidden sectors on each track of a disk. The default starting sector on a track with more than 63 sectors per track is sector 64. Unfortunately, given Windows block size, it means that, on average, one out of every eight blocks of data written to the disk will span two tracks, requiring a head seek to completely read the block. This slows down reading and writing operations. Aligning the partition tracks with the disk tracks eliminates this extra head seek and speeds up most hard disks.
Both Diskpar and Diskpart are easy-to-use command line utilities that determine the starting sector on each track and let you reset it. However, both utilities reformat the disks. Be sure to back up all the data you want to save and delete all partitions on the disk before you use them.
Check with your disk vendor before using Diskpar or Diskpart. Modern hard drives are not laid out simply and on some drives these utilities will produce little or no performance improvement.
Here are other things you can do to improve performance of Windows storage in general:
- Choose Spindles over capacity. With RAID, a lot of smaller disks can outperform a single large disk because you can stripe data across several disks.
- Speed matters. Faster disks mean higher performance. With important applications like Exchange, the difference is worth paying for.
- Monitor performance. If you experience disk latency of more than 20 microseconds, or if you have latency spikes of more than 50 microseconds that last more than a few seconds, consider making changes to your storage system.
You can download Microsoft's coverage of this in a white paper, Optimizing Storage for Exchange Server 2003.
Rick Cook has been writing about mass storage since the days when the term meant an 80 KB floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years, Cook has been a freelance writer specializing in storage and other computer issues.