3-3-3 RAID 5 Explained
Key Concepts
- RAID 5 Overview
- Data Striping
- Parity Information
- Fault Tolerance
- Performance
RAID 5 Overview
RAID 5 is a data storage virtualization technology that combines disk striping with parity to achieve both performance and fault tolerance. It requires a minimum of three disks and distributes data and parity information across all disks in the array.
Data Striping
Data striping in RAID 5 involves dividing data into blocks and distributing these blocks across multiple disks. This technique enhances read and write performance by allowing multiple disks to operate in parallel. Each block of data is written to a different disk, ensuring that no single disk becomes a bottleneck.
Parity Information
Parity information in RAID 5 is used to reconstruct data in the event of a disk failure. Parity is calculated based on the data blocks across all disks and is stored on a rotating basis across the disks. This means that each disk in the array will store a portion of the parity information at different times.
Fault Tolerance
RAID 5 provides fault tolerance by allowing the array to continue functioning even if one disk fails. When a disk fails, the system uses the parity information stored on the remaining disks to reconstruct the lost data. This ensures data integrity and availability, making RAID 5 suitable for environments where uptime is critical.
Performance
RAID 5 offers improved read performance due to data striping, as multiple disks can be read simultaneously. However, write performance is slightly reduced because parity information must be calculated and written with each data block. Despite this, RAID 5 remains a popular choice for applications requiring a balance of performance and fault tolerance.
Examples and Analogies
Think of RAID 5 as a team of workers building a wall. Each worker (disk) contributes a brick (data block) to the wall, and they also keep a record (parity information) of the bricks' positions. If one worker (disk) is absent, the team can still complete the wall by using the record to fill in the missing bricks. This ensures the wall (data) remains intact and functional.
Another analogy is a puzzle where each piece (data block) is placed by a different person (disk), and they all keep a note (parity information) of the piece's position. If one person (disk) loses their piece, the others can reconstruct it using their notes. This ensures the puzzle (data) can still be completed and enjoyed.