| Level |
Explanation |
Advantages |
Disadvantages |
Remarks |
| 0 |
Striping across disks |
Larger I/Os or throughput
Full utilization of disk array capacity
Good for read & write |
No fault tolerance
One disk fails, entire volume fails.
Cannot recover from failed disk. |
Usually 2-4 drives. Applications requiring high
performance but non –critical data and low cost. |
| 1 |
Mirroring |
Highest fault tolerance.
Good for read |
Higher cost |
Smaller applciations with high availability |
| 0 + 1 |
Striping + Mirroring |
Very high reliability
Good for read & write
High performance |
Higher cost |
Samller applications with high performance |
| 2 |
Inherently parallel mapping and
protection technique. Mostly it is not deployed because it needs special
disk futures. Disk production is not economical cost wise. |
| 3 |
Data striped across disks. Min. 3 disks are
required |
Cost is lower than other redundant levels |
Bottleneck for small I/O operations
RAID 3 is not found on all controllers. |
Large I/O request like CAD, CAM imaging. |
| 4 |
Similar to Raid 3. Unlike Raid 3 it wirtes parity
in a single disk. |
Parity data for whole array requires just one
disk. |
Bottleneck for small I/O operations due to |
Large file transfers |
| 5 |
Calculates parity, and writes the data in stripes
across disks. Rotational parity |
Smaller datafiles high throughput.
Even if one disk fails system will be up and runing.
Reasonable cost. |
Slower Write than Raid-3 and Raid-4.
Write performance poor. Recovery is slow. |
Very high read rate. Less write applications.
OLTP
File server
Web server |