Stands for redundant array of independent disks, a technology for implementing fault tolerance on a disk subsystem by using data redundancy, either using software or using a separate hardware RAID storage unit.
A number of RAID levels are defined, but Microsoft Windows NT and Windows 2000 support only three of them - RAID 0, RAID 1, and RAID 5. These are the most popular implementations of RAID. The RAID levels that are presently defined include the following:
Graphic R-2. Common RAID file types.
RAID is implemented using the Windows NT Server administrative tool Disk Administrator or the Disk Management portion of the Computer Management tool in Windows 2000. RAID cannot be implemented on Windows NT Workstation or Windows 2000 Professional.
Windows NT and Windows 2000 provide a software-based RAID solution in which the operating system software enables various types of RAID functionality on the internal disk subsystem, usually a Small Computer System Interface (SCSI) disk subsystem. The other type of RAID solution is hardware-based RAID, in which stand-alone external RAID-5 disk arrays are usually attached to servers using SCSI or fiber channel connections.
When you buy a hardware RAID-5 unit, be sure that it has hot-rebuild, hot-swap, and hot-spare capabilities. These features protect business-critical data and ensure high availability.