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Difference between RAID 1 and RAID 2

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1. RAID 1: RAID 1 is also called mirroring of data. Because it replicates the data from drive 1 to drive 2. One half of the drive is used to store the data and Another one is act as a mirror to the already stored data. This level provide 100% redundancy in case of failure. Advantage – Good fault tolerance i.e.. ability of maintaining functionality even if one disk fails. Disadvantage – It is Expensive Because extra drive is required for mirroring.  
2. RAID 2: RAID 2 consists of Bit-Level Striping. It records Error Correction Code (ECC) using hamming code parity. In this level each data bit in a word is recorded on separate disk and ECC codes of the data words are stored on a different set of disks. Advantage – In case of Error Correction it uses hamming code. Disadvantage – It has complex structure and high cost due to extra drive.  
Difference between RAID 1 and RAID 2: 

SR.NO. RAID 1 RAID 2
1. RAID 1 stands for Redundant Array of Independent Disk level 1. RAID 2 stands for Redundant Array of Independent Disk level 2.
2. In RAID 1 technology, Disk Mirroring is used. In RAID 2 technology, Bit-Level Striping is used.
3. In RAID 1, one half of drive is used for storing data and another half is just a mirror for already store data In RAID 2, each data bit in a word recorded on a separate disk and ECC codes are stored on different disk
4. Good Fault tolerance as compared to RAID 2. Fault tolerance is not so good.
5. Hamming Codes are not used. Hamming Codes are used for Error Correction.
6. Extra Drive is required for mirroring. Extra Drive is required for Error Correction.

RAID (Redundant Array of Independent Disks) 1 and RAID 2 are both methods of configuring multiple disks in a computer system to provide fault tolerance and data redundancy. However, the main difference between RAID 1 and RAID 2 lies in how they distribute data and parity across the disks.

  1. RAID 1, also known as disk mirroring, involves the duplication of data on two or more disks. In this configuration, all data is written to both disks simultaneously, so that each disk contains an identical copy of the data. This provides fault tolerance, as if one disk fails, the system can continue to operate with the remaining disk(s) until the failed disk is replaced. RAID 1 does not use parity data, and thus there is no need for a dedicated parity disk.
  2. In RAID 2, data is divided into individual bits and then striped across multiple disks, with a dedicated parity disk that stores the parity information for all the data disks. The parity information is generated using Hamming code, which allows for single-bit error correction and double-bit error detection. This provides fault tolerance, as if one disk fails, the system can continue to operate with the remaining disks and the parity information until the failed disk is replaced.

Overall, RAID 1 is simpler and easier to implement than RAID 2, as it only requires duplication of data across multiple disks without the need for parity information. RAID 2, on the other hand, is rarely used in modern storage systems due to its complexity and high overhead. In general, RAID 1 is a good choice for applications that require high availability and data protection, while RAID 2 is not recommended for most applications due to its low efficiency and complexity.


Last Updated : 03 May, 2023
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