RAID 50 (Striping RAID 5 Arrays)
RAID 50 incorporates the technique of striping (RAID 0) across multiple RAID 5 arrays. RAID 5 uses the striping technique in combination with single parity to provide high fault tolerance. At least six physical disks are required to create a RAID 50 array, as shown in Figure 1.
Table 1 describes RAID 50 across a number of parameters.
Parameter |
Rating |
Description |
|||||||
Read Performance |
|
Read/write performance is similar to RAID 5. Read performance is good (due to striping) but write performance is comparatively lower because of the need to calculate and write single parity information. |
|||||||
Write Performance |
|
||||||||
Fault Tolerance |
|
RAID 50 arrays can tolerate the failure of one physical disk in each RAID 5 set. The failed physical disk must be replaced to ensure continued fault tolerance. Otherwise, the two or more working physical disks in the partially degraded RAID 5 set become multiple points of failure for the entire array. |
|||||||
Efficient use of disk capacity |
|
When the minimum six physical disks are used in a RAID 50 array, approximately 33% of the combined disk capacity (one physical disk per RAID 5 set) is used for redundancy. The capacity efficiency increases as the number of physical disks increases (because only one physical disk is used per RAID 5 set for redundancy irrespective of the number of physical disks in the RAID 5 set). |
|||||||
Automatic rebuild |
|
Available |
|||||||
Minimum number of drives |
|
6 |
Figure 1 describes RAID 50.
Figure 1 RAID 50: Illustration
Note: An Adobe Flash® demonstration of RAID 50 is not provided. RAID 50 incorporates the technique of striping (RAID 0) across multiple RAID 5 arrays. View demonstrations for RAID 0 and RAID 5 for an understanding of how RAID 50 arrays are built.