Terse version by DGG adapted from: www.microsoft.com/technet/prodtechnol/windows2000serv/maintain/optimize/11w2kadb.mspx no longer available?


AKA disk striping, uses multiple disks and spreads the data across them for individual I/O operations.
RAID 0 is sometimes used to emulate a larger disk.

Performance improvement comes from :

  1. Seek time is reduced since it is proportional to the number of cylinders the head must move and the seek times of multiple drives will be overlapped. Increasing the number of disks reduces the number of cylinders that the head needs to move given the same storage capacity system.

    Rotational latency (the time for the disk to rotate to the requested sector from the sector it was at when the head reaced the correct cylinder), Is minimized in for the next sector since once the heads arrived on-cylinder, subsequent sectors ( not necessarily requested [yet] in the track were read to the onboard cache. With 2 drives acting as one the cache is doubled!

    This assumes that the less expensive multiple disks are of the same performance family as the anticipated large disk.
    Upgrading to a higher performance family, for example 10k (10,000 RPM), may reduce the transfer rate. as much may be 50% faster then 75,00RPM disks.
    The specifications of the particular disk under consideration must be examined recording density contributes to the amount of data stored per track.
    Track-to-track and maximum seek time may be significantly shorter in higher performance disks. Although more expensive, higher performance disks are usually built with higher expected duty cycle and larger mean time between failure.

    striping decreases reliability since a failure of either disk causes all data to be unavailable.

    Other considerations include the availability of controller channels and there is an increasing concern regarding power and related cooling requirements.

    Implementing RAID on Windows 2000 Servers

    The boot and system volumes can't be part of a striped set*. Mirroring can be used on any volume including the boot and system volumes*.
    the volume to be mirrored must be a simple volume, and must have an area of unallocated space on a second dynamic drive. See Dynamic Disks