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RAID 0 (also known as a stripe set or striped volume) splits ("stripes") data evenly across two or more disks, without parity information, redundancy, or fault tolerance. Since RAID 0 provides no fault tolerance or redundancy, the failure of one drive will cause the entire array to fail, due to data being striped across all disks.
RAID 01, also called RAID 0+1, is a RAID level using a mirror of stripes, achieving both replication and sharing of data between disks. [3] The usable capacity of a RAID 01 array is the same as in a RAID 1 array made of the same drives, in which one half of the drives is used to mirror the other half.
RAID (/ r eɪ d /; redundant array of inexpensive disks or redundant array of independent disks) [1] [2] is a data storage virtualization technology that combines multiple physical data storage components into one or more logical units for the purposes of data redundancy, performance improvement, or both.
A parity drive is a hard drive used in a RAID array to provide fault tolerance. For example, RAID 3 uses a parity drive to create a system that is both fault tolerant and, because of data striping, fast. [1] Basically, a single data bit is added to the end of a data block to ensure the number of bits in the message is either odd or even. [2]
All implementations of RAID, redundant array of independent disks, except RAID 0, are examples of a fault-tolerant storage device that uses data redundancy. A lockstep fault-tolerant machine uses replicated elements operating in parallel. At any time, all the replications of each element should be in the same state.
RAID 5E, RAID 5EE, and RAID 6E (with the added E standing for Enhanced) generally refer to variants of RAID 5 or 6 with an integrated hot-spare drive, where the spare drive is an active part of the block rotation scheme. This spreads I/O across all drives, including the spare, thus reducing the load on each drive, increasing performance.
The result is increased reliability in a RAID array. In a stand-alone configuration TLER should be disabled. As the drive is not redundant, reporting segments as failed will only increase manual intervention. Without a hardware RAID controller or a software RAID implementation to drop the disk, normal (no TLER) recovery ability is most stable.
For RAID subsystems, data integrity and fault-tolerance requirements also reduce the realized capacity. For example, a RAID 1 array has about half the total capacity as a result of data mirroring, while a RAID 5 array with n drives loses 1/n of capacity (which equals to the capacity of a single drive) due to storing parity information. RAID ...