❑ RAID(Redundant Array of Inexpensive/Independent Disk) : A technique combining multiple disks into one.
* Benefits: Reduced costs, improved safety, improved performance.
❑ Type of RAID implementation
❍ Hardware RAID : It is controlled by hardware. High performance. High price.
❍ Software RAID : It is controlled by OS. Low performance. Low price.
❑ RAID is divided into RAID 0~6 according to the operation method, but RAID 0, 1, 5, 6 are mainly used.
❑ Linear RAID : It uses multiple disks as a single disk to expand storage capacity.
❍ If the first disk is full, it stores the data on the next disk.
❑ RAID 0(Striping) : It distributes and stores data on multiple hard disks(parallel).
❍ Improved storage speed.
❍ If one of the disks has a problem, the entire data is corrupted.
❑ RAID 1(Mirroring) : It stores the same data redundantly on each disk.
❍ Data defects are allowed.
❍ N times storage space is required.
❑ RAID 5 : RAID 0 + One Parity disk.
❍ Pairty : Information used to recover data.
❍ At least three hard disks are required(The one is for Parity disk).
❍ This allows one disk defect(not recoverable when two or more disk defects occur).
❍ It uses as much space as number of disks -1.
❑ RAID 6 : RAID 0 + Two Parity disk.
❍ Since two parity disks are used, data can be recovered even if two disk defects occur.