RAID stands for "redundant array of independent disks" or "redundant array of inexpensive disks". It is a data storage virtualization technology that combines multiple physical disk drive components into one or more logical units for the purposes of data redundancy, performance improvement, or both. RAID can be used to store the same data in different places on multiple hard disks or solid-state drives (SSDs) to protect data in the case of a disk failure. RAID levels refer to different schemes or data distribution layouts, named by the word "RAID" followed by a number, such as RAID 0 or RAID 1. Each RAID level provides a different balance among the key goals of reliability, availability, performance, and capacity.
There are several types of RAID configurations, including:
- RAID 0: Offers the fastest read/write speeds and maximum availability of raw storage capacity, but does not provide any data redundancy.
- RAID 1: Mirrors data across two or more disks to provide redundancy, but at the cost of reduced storage capacity.
- RAID 5: Balances performance and redundancy by splitting data into groups across all available drives and creating distributed parity, where data calculations are stored across the drives so that any one drive may fail, and the data or parity on the other drives can reconstitute what was lost on the failed drive.
- RAID 6: Similar to RAID 5, but with an additional parity block, allowing for recovery from the failure of two drives.
- RAID 10: Combines RAID 1 and RAID 0 to provide both redundancy and performance.
RAID can be implemented using special hardware or software, and can improve performance, help protect data in case of a crash, and provide scalability and cost-effectiveness. However, some RAID configurations can be expensive to implement and may have performance limitations.
