These controller support RAID levels 0, 1, 10, 5, 6, 50 and 60. See below for a short description of these RAID types. Additional detail can be found in the RAID controller software user's guide.
Level 0: Often called "striping," is a performance-oriented data mapping technique. Data written to the array are divided into stripes and written across the disks of the array. This procedure enables high I/O performance at a low cost but provides no redundancy.
Level 1: Often called "mirroring," provides redundancy by writing identical data to each member disk of the array. Level 1 operates with two disks that may use parallel access for high data-transfer rates when reading, but more commonly operates independently to provide high I/O transaction rates. Level 1 provides very good data reliability and improves performance for read-intensive applications but at a relatively high cost. Minimum number of drives is two.
Level 5: RAID Level 5 is the most common type of RAID. By distributing parity across some or all of an array's member disk drives, RAID level 5 eliminates the write bottleneck inherent in level 4. As with level 4, the result is asymmetrical performance, with reads substantially outperforming writes. Level 5 is often used with write-back caching to reduce the asymmetry. Because parity data must be skipped on each drive during reads, however, the performance for reads tends to be considerably lower than a level 4 array. Minimum number of drives is three.
Level 6: RAID Level 6 extends RAID 5 by adding an additional parity block, thus it uses block-level striping with two parity blocks distributed across all member disks. The goal of this duplication is to improve fault tolerance; RAID 6 can handle the failure of any two drives in the array while other single RAID levels can handle at most one fault. Performance-wise, RAID 6 is generally slightly worse than RAID 5 in terms of writes due to the added overhead of more parity calculations, but may be slightly faster in random reads due to spreading of data over one more disk. Minimum number hard disks is three.
Level 10: RAID level 10 employs the features of levels 1 and 0. The advantages are faster data access (like RAID 0), and single-drive fault tolerance (like RAID 1). RAID 10 requires twice the number of disks (like RAID 1), but it offers some performance improvements by striping, then mirroring the striped array. RAID 10 stripes the blocks of data to each RAID 1 array. Each RAID 1 array then duplicates its data to its other drive. Minimum number of drives is four.
Level 50: RAID level 50 employs the features of levels 5 and 0. RAID 50 includes both parity and disk striping across multiple drive groups. RAID 50 is best implemented on two RAID 5 disk arrays with data striped across both arrays. RAID 50 can sustain one to four drive failures while maintaining data integrity if each failed disk is in a different RAID 5 array. Minimum number of drives is six.
Level 60: RAID level 60 employs the features of levels 6 and 0. A RAID 60 array combines the straight block-level striping of RAID 0 with the distributed double parity of RAID 6. That is, a RAID 0 array striped across RAID 6 elements. A RAID 60 virtual disk can survive the loss of two disks in each of the RAID 6 sets without losing data. It works best with data that requires high reliability, high request rates, high data transfers, and medium-to-large capacity. Minimum number of drives is eight.
This applies to: