Suppose you have 4 identical disk drives available to config

Suppose you have 4 identical disk drives available to configure in a RAID. How could you configure these drives to provide a single logical unit with the maximum amount of usable storage space? How could you configure them to provide a single logical unit with protection against the loss of 2 of the 4 drives?

Solution

There are generally few levels available in RAID to allow you to combine different physical data drives to form a logical drive to provide redundancy. RAID level 0-6 and 10 are available for forming the logical drive. Here given that there are 4 identical disk drives and these drives are to be combined to form the required logical unit with the maximum amount of usable storage space

4 drives can be formed as 2 RAID 0 logical units and 1 RAID 5 logical unit and here RAID level 5 has more usable storage space consider if drives are of 1 TB each then RAID 5 will have 3TB where as RAID 0 will have 1 TB for each i.e., 2TB . But here in RAID level 5, only if the one hard drive is crashed then only by using the parity bit stored data can be retrieved.

If two drives are lost then RAID level 5 implementation is not useful hence we prefer RAID level 6 which is same as RAID level 5 but can be able to retrive data even two drives been failed..