What is RAID?

RAID is stand for Redundant Array of Independent Disks. RAID is now used as an umbrella term for computer data storage schemes that can divide and replicate data among multiple hard disk drives. RAID's various designs all involve two key design goals: increased data reliability or increased input/output performance. When multiple physical disks are set up to use RAID technology, they are said to be in a RAID array. This array distributes data across multiple disks, but the array is seen by the computer user and operating system as one single disk. RAID can be set up to serve several different purposes

RAID Comparison Chart

RAID Level Min Drives Protection Description Strengths Weaknesses Typical Apps 　RAID 0 2 None Data striping without redundancy Highest performance No data protection; One drive fails, all data is lost High End Workstations, Data Logging, Real-Time Rendering, Transitory Data 　RAID 1 2 Single Drive Failure Disk mirroring Very high performance; Very high data protection; Very good on write performance High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required Operating Systems, Transactional Databases 　RAID 5 3 Single Drive Failure Block-level data striping with distributed parity Best cost/performance for transaction-oriented networks; Very high performance, very high data protection; Supports multiple simultaneous reads and writes; Can also be optimized for large, sequential requests Write performance is slower than RAID 0 or RAID 1 Data Warehousing, Web, Archiving, Basic File Servers, Disk Backup 　RAID 6 4 2 Drive Failure Same as RAID 5 with x2 Parity distributed across an extra drive Offers Solid Performance with the additional fault tolerance of allowing availability to data if 2 disks in a RAID group to fail.  Recommended to use more drives in RAID group to make up for performance and disk utilization hits compared to RAID 5 Must use a minimum of 5 drives with 2 of them used for parity so disk utilization is not as high as RAID 3/5.  Performance is slightly lower than RAID 5 High Availability Solutions, Mission Critical Apps, Servers with Large Capacity Requirements 　RAID 10 4 1 Disk Per Mirrored Stripe (not same mirror) Combination of RAID 0 (data striping) and RAID 1 (mirroring) Highest performance, highest data protection (can tolerate multiple drive failures) High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required; Requires minimum of four drives Databases, Application Servers 　RAID 50 6 1 Disk Per Mirrored Stripe Combination of RAID 0 (data striping) and RAID 5 (Single Parity Drive) Highest performance, highest data protection (can tolerate multiple drive failures) High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required; Requires minimum of four drives Databases, File Servers, Application Servers, 　RAID 60 8 2 Disks Per Mirrored Stripe Combination of RAID 0 (data striping) and RAID 6 (Dual Parity Drives) Highest performance, highest data protection (can tolerate multiple drive failures) High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required; Requires minimum of four drives High Availability Solutions, Mission Critical Apps, Servers with Large Capacity Requirements