RAID Levels

RAID = Redundant Array of Independent Discs.
A RAID system is a collection of hard drives joined together using a RAID level definition.

• RAID can be used to stripe drives together to give more overall access speed (level 0).
• RAID can be used to mirror drives (level 1).
• RAID can be used to increase uptime of your overall storage by striping drives together and then keeping parity data, if a drive should fail the system keeps operating (level 5 or 6).

RAID levels 5 and 6 are most commonly used, primarily for uptime purposes and its ability to join together (say) 14 drives, giving a large storage block.

Read about RAID levels below and for more detailed information visit the specific RAID Education page on our site at Sunstar Company, Inc.

• Level 0
  Striped Disk Array without Fault Tolerance: Provides data striping (spreading out blocks of each file across multiple disk drives) but no redundancy. This improves performance but does not deliver fault tolerance. If one drive fails then all data in the array is lost.
• Level 1
  Mirroring and Duplexing: Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks.
• Level 2
  Error-Correcting Coding: Rarely used, with data striped at the bit level rather than the block level.
• Level 3
  Bit-Interleaved Parity: Provides byte-level striping with a dedicated parity disk. Rarely used as it cannot service simultaneous multiple requests.
• Level 4
  Dedicated Parity Drive: A commonly used implementation of RAID, Level 4 provides block-level striping (like Level 0) with a parity disk. If a data disk fails, the parity data is used to create a replacement disk. A disadvantage to Level 4 is that the parity disk can create write bottlenecks.
• Level 5
  Block Interleaved Distributed Parity: Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance. Possibly the most popular implementations of RAID.
• Level 6
  Independent Data Disks with Double Parity: Provides block-level striping with parity data distributed across all disks. Very popular at this time.
• Level 0+1
  A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.
• Level 10
  A Stripe of Mirrors: Not one of the original RAID levels, multiple RAID 1 mirrors are created, and a RAID 0 stripe is created over these.

Please feel free to contact us at Sunstar Company at: info@sunstarco.com or 800.663.5523

Many Thanks

Gavin

www.sunstarco.com