RAID Levels - Easy to Understand

             RAID in Windows 2008 is implemented not only for fault tolerance but also for improving the performance. It is a technology that provides storage functions and reliability through redundancy. Therefore, you can define RAID as group of technologies that use multiple drives, in multiple  configurations, to store redundant data.

 In Windows Server 2008 , two types of RAID are implemented:
  
                      - Software based RAID : Specifies that to implement RAID array the system processor uses special software routines. This type of RAID is usually implemented at the OS Level.

                      - Hardware based RAID : Specifies that to implement RAID array controllers use proprietary disk layouts.

RAID Levels:

 RAID 0  (Min. 2 disks required)

     Provides no fault tolerance but helps in improving performance as read and write operations occur on all drives simultaneously. However, in case of failure of one disk causes loss of data on all volumes.

RAID 1  (Min. 2 disks required)

    Provides increased fault tolerance. In case of failure, there is no loss of data as long as one disk remains operational.

RAID 5  (Min. 3 disks required)

    Ensures that a block and its equivalent information are not stored on the same disk. This feature is very useful as in case of failure, it can rebuild the missing data when the drive is repaired or replaced.


[You should note that apart from the RAID levels that I listed above , There are 3 other types of RAID levels, namely:  RAID 3, RAID 4 and RAID 6. These are not implemented in Windows Server 2008]