Question

Compare RAID level 1 and RAID level 5 on the basis of following parameters.

1. Fault Tolerance
2. Performance in terms of read and write operations
3. Suitable application types

Answer 1

RAID Level 1)

RAID 0 is simple disk striping. All the data is spread out in chunks across all the disks in the RAID set. RAID 0 offers great performance because you spread the load of storing data onto more physical drives. It also has the lowest cost of all the RAID types because it uses disk space only to store data. Because there is no parity generated for RAID 0, there is no overhead to write data to RAID 0 disks.

However, RAID 0 has the worst data protection of all the RAID levels. When a disk fails, data on that disk is unavailable until it can be rewritten from another drive.

a. RAID 0 is not fault-tolerant. If one drive fails, all data in the RAID 0 array are lost. It should not be used for mission-critical systems.

b. RAID 0 offers great performance, both in read and write operations. There is no overhead caused by parity controls.

c. RAID 0 is ideal for non-critical storage of data that have to be read/written at a high speed, such as on an image retouching or video editing station.

If you want to use RAID 0 purely to combine the storage capacity of twee drives in a single volume, consider mounting one drive in the folder path of the other drive. This is supported in Linux, OS X as well as Windows and has the advantage that a single drive failure has no impact on the data of the second disk or SSD drive.

RAID Level 5)

RAID 5 uses disk striping with parity. The data is striped across all the disks in the RAID set, along with the parity information needed to reconstruct the data in case of disk failure.

RAID 5 is the most common RAID method because it achieves a good balance between performance and availability. RAID 5 requires at least three physical disks.

a. If a drive fails, you still have access to all data, even while the failed drive is being replaced and the storage controller rebuilds the data on the new drive. This is complex technology. If one of the disks in an array using 4TB disks fails and is replaced, restoring the data (the rebuild time) may take a day or longer, depending on the load on the array and the speed of the controller. If another disk goes bad during that time, data are lost forever.

b. Read data transactions are very fast while write data transactions are somewhat slower (due to the parity that has to be calculated).

c. RAID 5 is a good all-round system that combines efficient storage with excellent security and decent performance. It is ideal for file and application servers that have a limited number of data drives.