RAID stands for Redundant Array of Independent Disks, which is a technology that combines multiple physical disks into a logical unit that provides improved performance, reliability, and storage capacity. RAID levels are different ways of organizing and distributing data across the disks in a RAID array. Each RAID level has its own advantages and disadvantages, depending on the requirements and trade-offs of the system.
RAID 6 is a RAID level that uses block-level striping with double parity. This means that data is divided into blocks and distributed across all the disks in the array, and two sets of parity information are calculated and stored on different disks. Parity is a method of error detection and correction that can reconstruct the data in case of disk failure. RAID 6 can withstand the failure of up to two disks without losing any data, which makes it suitable for a private cloud that requires high fault tolerance. RAID 6 also maximizes the storage capacity of its drives, as it only uses two disks for parity and the rest for dat a. The storage capacity of a RAID 6 array is equal to (n-2) x S, where n is the number of disks and S is the size of the smallest disk.
RAID 0, RAID 1, RAID 5, and RAID 10 are other RAID levels, but they do not meet the requirements of the private cloud. RAID 0 uses striping without parity, which improves performance but does not provide any redundancy or fault tolerance. RAID 0 cannot withstand any disk failure, as it would result in data loss. RAID 1 uses mirroring, which copies the same data to two or more disks. RAID 1 provides high reliability and fast read performance, but it wastes half of the storage capacity for redundancy. RAID 1 can only withstand the failure of one disk in each mirrored pair. RAID 5 uses striping with single parity, which distributes data and parity across all the disks in the array. RAID 5 provides a balance of performance, reliability, and storage capacity, but it can only withstand the failure of one disk. RAID 10 is a combination of RAID 1 and RAID 0, which creates a striped array of mirrored pairs. RAID 10 provides high performance and reliability, but it also wastes half of the storage capacity for redundancy. RAID 10 can withstand the failure of one disk in each mirrored pair, but not more than that.
For more information on RAID levels, you can refer to the following sources:
CompTIA Cloud+ CV0-003 Certification Study Guide, Chapter 4, Storage Technologies, page 791 Cloud+ (Plus) Certification | CompTIA IT Certifications2