Question

Compare the concept of RAID and describe its various levels in about 300 words in a Table on the following parameters :

1. Cost

2. Availability

3. Response time

4. Reliability

Answer 1

Redundant arrays of independent disks(RAID) is used to take multiple storage devices and make them work as a single device. This allows data to be backed up and to protect data when there is a disaster. RAID is used to provide higher reliability and higher performance.

RAID LEVEL	Description
RAID O	This is the cheapest of all the RAID available. They do not provide any Redundancy. Raid 0 is easily available. Since data is stripped on all the disks of an array this provides better response time. It is less reliable then rest of the RAID level
RAID 1	RAID 1 is more expensive than RAID 0 but cheaper than other RAID levels. They are readily available for usage. Response time is better here with a good read and write speed. It is more reliable than the RAID 0
RAID 2	RAID 2 is used for error detection and correction. It cost lesser and is easily available. This RAID level provides faster Transfer rate and response time. It is much more reliable then RAID 1.
RAID 3	RAID 3 recognises when a disk has been read correctly for error detection. We can know whether a disk has been read by reading the parity value. If it is 1 then it has been read and if it is 0 then it not has been read. The cost of RAID 3 is much more than RAID 2. It is also available easily. The response time is a bit slower as the time is wasted by checking the parity value. It is not a cheap or reliable solution for data storage
RAID 4	It is just like RAID 3 except the fact that RAID 4 stores the parity value in another disk. RAID 4 is not cheap and is not easily available. The response time increases as there is a need to check other disks as well. It is also not reliable
RAID 5	It is a better version of RAID 4 as it partitions the disk and the parity in "n+1" disk instead of storing the parity in another disk. It is costly and is easily available. The response time is much more as there is no need to store data in another disk. This makes the read and write time faster. It is much more reliable than other disks
RAID 6	It is like RAID 5 except the fact that it stores redundant into another disk to prevent data from any disk failure. It is costly and is readily available. The response time is much low than RAID 5 as there is a need for another disk. It is also reliable.