High available (HA) storage is very important for any Exchange deployment. Although with DAGs and AutoReseed a disk failure might not be as serious as before, losing a disk that holds Exchange data can still be very damaging for some organizations.

Redundancy is the key feature of HA storage, and is achieved by storing data in more than one place to eliminate single points of failure. HA storage systems can be used anywhere from a single server to a complex virtual environment. There are typically two ways to achieve high available storage: RAID and enterprise-level storage clusters.

RAID was initially defined as Redundant Array of Inexpensive Drives. However, RAID was indeed expensive initially, so I became Independent. Since the costs of disks have come down significantly, RAID has become more popular, and is now embedded in most desktop and server motherboards. Storage RAIDs were mainly designed to offer better performance, improve fault tolerance, and for...