You'll often want to give important data increased protection from drive failures. To do this, you can use RAID technology to add fault tolerance to your file systems. With RAID you increase data integrity and availability by creating redundant copies of the data. You can also use RAID to improve your disks' performance. Different implementations of RAID technology are available. These implementations are described in terms of levels. Currently, RAID levels 0 to 5 are defined. Each RAID level offers different features. Windows Server 2003 supports RAID levels 0, 1, and 5.
Table 12-2 provides a brief overview of the supported RAID levels. This support is completely software-based. Table 12-2. Windows Server 2003 Support for RAID
The most common RAID levels in use on servers running Windows Server 2003 are level 1 disk mirroring and level 5 disk striping with parity. Disk mirroring is the least expensive way to increase data protection with redundancy. Here, you use two identically sized volumes on two different drives to create a redundant data set. If one of the drives fails, you can still obtain the data from the other drive. On the other hand, disk striping with parity requires more disks ”a minimum of three ”but offers fault tolerance with less overhead than disk mirroring. If any of the drives fail, you can recover the data by combining blocks of data on the remaining disks with a parity record. Parity is a method of error checking that uses an exclusive OR operation to create a checksum for each block of data written to the disk. This checksum is used to recover data in case of failure.
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