Disk geometry
"Disk subsystem bottlenecks cause more performance problems than server-side CPU or RAM deficiencies, and a poorly designed disk subsystem can leave your organization vulnerable to hardware malfunctions."
This is so true! As memory chips become cheaper and consolidation dictates more users per server, the disk subsystem turns into the main cause of performance problems. The key to a system without problems is a proper planning and design. The document from which I extracted the beginning sentence, Optimizing Storage for Exchange Server 2003, is a good source of information.
One of the improvements you can make on your storage is to align the disks. Microsoft provides a tool, Diskpar, which allows to align the disk tracks with sector tracks. For partitions created by Windows 2000 and Windows Server 2003, the default starting sector for disks that have more than 63 sectors per track is the 64th sector, causing one out of every eight blocks of data written to your disk to span two disk tracks. Diskpar can increase disk performance as much as 20 percent, but you should always consult your hardware vendor before using this tool. Some disk configurations will have no benefit from the tool.
One fine example of information provided by the storage vendor is HP. Just take a look at this document: HP StorageWorks Enterprise Virtual Array 5000 and Microsoft® Exchange Server 2003: storage performance and configuration — white paper.
The Diskpar utility can be found in the Windows 2000 Server Resource Kit. With the release of Windows Server 2003 SP1, diskpart now includes this functionality. The new syntax for creating partitions with diskpart is:
create partition primary [size=N] [offset=N] [ID={Byte | GUID}] [align=N] [noerr]
Of course, you can still use diskpar:
Usage: diskpar [ -i | -s ] DriveNumber
-i: query drive layout and partition information
-s: set partition information (only used on raw drive please)