Most people tend to understand RAID as a type of technology that enables you to backup data automatically. While this is partially true, it is by no means the whole picture – and the first step to understanding what RAID is all about is realizing that there are several standardized ‘levels’ involved that are unique in their own ways.
While RAID levels technically extend from 0 upwards – the most common varieties in use are RAID 0, 1, 5, and 6. Knowing what the advantages and disadvantages of each of these levels are could help you to choose between them.
Contrary to what you may expect, RAID 0 has no redundancy whatsoever, so there is no backup of data and if a disk fails then all data will be lost. However because it uses striping it provides superior read and write performance – better than any other level.
Unlike RAID 0, RAID 1 mirrors data exactly across the drives so that there is always an exact backup remaining. In terms of speed it is similar to that of a single drive, but because all data is written twice it will only ever utilize half of the total storage space available.
Essentially RAID 5 utilizes ‘parity’ to provide a backup of data that is stored on it. It does not mirror data, but instead spreads parity data across all drives allowing it to recalculate the data on any other block if it fails. In a RAID 5 system at least 3 drives are required, and it can withstand a single drive failing without losing any data. However while the read speeds are fast, the write speeds tend to be slower as the parity needs to be calculated each time data is written.
Basically RAID 6 is very similar to RAID 5 but the parity data is written twice – providing a backup of itself in a way. Because of the double parity, RAID 6 setups require at least 4 hard drives, but can withstand up to 2 hard drives failing without losing any data. Just like RAID 5, it has fast read speeds but slow write speeds due to the parity.
Now that you understand the differences between the various RAID levels, you should be able to quite easily find the best compromise between redundancy, performance and cost. Of course RAID systems can still be subject to data loss under certain conditions, but there are RAID recovery options that you can pursue if you suspect a RAID array failure. On the whole using RAID drives is a lot more secure, and will provide your data with a certain amount of safety.