RAID ("Redundant Array of Independent/Inexpensive Disks") is an advanced hard drive configuration system, composed of two drives or more, that is designed to facilitate redundancy (also known as fault) by distributing data across multiple hard drives. This redundancy is crucial for businesses as it is designed to protect their data if one (and in some situations, even two) hard drive(s) fail physically.
Although they are designed to speed up data access and prevent data loss, even RAIDs are subject to failure. Common RAID failures include: problems originating in the controller, RAID rebuild errors, loss of configuration settings for the server, server registry configuration loss, accidental replacement of media components, and physical hard drive failure(s) within the unit.
Therefore, it is important not to mistakenly substitute RAIDs for proper and regular back-up practices.
The most common RAID configurations that are routinely handled in our fully equipped, class-100 clean room data recovery lab are:
RAID 0: Data is striped across multiple hard drives. This configuration provides the utmost speed. The main drawback of this system is its lack of redundancy.
RAID 1: Data is written to and read on both hard drives simultaneously (drives are mirrored). Because the data is identical on both drives, we normally treat RAID-1 recoveries as a single drive recovery.
RAID 5: This type of RAID offers both data redundancy and faster performance. With this configuration, any drive can crash and the data should still remain intact.
RAID 6: Similar to RAID-5, this RAID level provides distributed parity information, but it allows for two drives to fail while keeping the rest of the data intact. This configuration is normally presented in business-oriented/focused NAS units.
RAID 10: This configuration combines RAID 1 and 0, so the data is stripped (RAID 0) across mirrored/identical pairs (RAID 1) of drives.
RAID 0 + 1: This configuration is opposite to RAID 10; the data is identical on both stripped pairs of drives.