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

Oracle files

Raid Levels

Parameter files

5 , 0+1 , ANY

Control files

5, 0+1, ANY

Redo logs

1, 0+1

System Tablespace

5,1, 0+1

Temporary Tablespace

0

Rollback Tablespace

5

Data files

5 , 0+1

Index Tablespace

5, 0+1