Which of the following is the minimum hard disk configuration required to configure raid 6?

In a RAID 0 system, data are split up into blocks that get written across all the drives in the array. By using multiple disks (at least 2) at the same time, this offers fast read and write speeds. All storage capacity can be fully used with no overhead. The downside to RAID 0 is that it is NOT redundant, the loss of any individual disk will cause complete data loss. Thus, it is not recommended to use unless the data has no value to you.

RAID 1 is a setup of at least two drives that contain the exact same data. If a drive fails, the others will still work. It is recommended for those who need high reliability. An additional benefit of RAID 1 is the high read performance, as data can be read off any of the drives in the array. However, since the data needs to be written to all the drives in the array, the write speed is slower than a RAID 0 array. Also, only capacity of a single drive is available to you.

RAID 5 requires the use of at least 3 drives, striping the data across multiple drives like RAID 0, but also has a “parity” distributed across the drives. In the event of a single drive failure, data is pieced together using the parity information stored on the other drives. There is zero downtime. Read speed is very fast but write speed is somewhat slower due to the parity that has to be calculated. It is ideal for file and application servers that have a limited number of data drives.

RAID 5 loses 33 percent of storage space (using three drives) for that parity, but it is still a more cost-effective setup than RAID 1. The most popular RAID 5 configurations use four drives, which lowers the lost storage space to 25 percent. It can work with up to 16 drives.

RAID 6 is like RAID 5, but the parity data are written to two drives. That means it requires at least 4 drives and can withstand 2 drives dying simultaneously. Read speed is as fast as RAID 5, but write speed is slower than RAID 5 due to the additional parity data that have to be calculated. RAID 6 is a very good option for a standard web server, where most of the transactions are reads. But it is not recommended for a heavy write environment, such as a database server.

RAID 10 consists of a minimum for four drives and combine the advantages of RAID 0 and RAID 1 in one single system. It provides security by mirroring all data on secondary drives while using striping across each set of drives to speed up data transfers. This means that RAID 10 can provide the speed of RAID 0 with the redundancy of RAID 1. You can lose any single drive, and possibly even a 2nd drive without losing any data. Just like RAID 1, only half of the total drive capacity is available, but you will see improved read and write performance and also have the fast rebuild time of RAID 1. Compared to large RAID 5 or RAID 6 arrays, this is an expensive way to have redundancy though.