RAID Storage Array Documentation

What is RAID?

RAID (Redundant Array of Independent Disks) is a technology that combines multiple hard drives into a single logical storage unit. This technology improves data read/write performance and reliability.

Why Use RAID?

1. Improved Performance
   • Increases data transfer speeds through parallel disk read/write
   • Reduces I/O bottlenecks
2. Enhanced Data Reliability
   • Provides fault tolerance through data redundancy
   • Protects data in case of disk failure
3. Increased Storage Capacity
   • Combines multiple physical disks into larger logical volumes
   • Simplifies storage management

Common RAID Levels and Calculation Formulas

RAID 0 (Striping)

• Features: Distributes data evenly across all disks
• Advantages: Maximizes storage space and performance
• Disadvantages: No redundancy, single disk failure causes total data loss
• Capacity Formula:

  Total Capacity = Number of Disks × Single Disk Capacity
  

RAID 1 (Mirroring)

• Features: Data is completely duplicated across two or more disks
• Advantages: Provides complete data redundancy
• Disadvantages: Low storage efficiency, only 50%
• Capacity Formula:

  Total Capacity = Single Disk Capacity
  

RAID 5 (Striping with Parity)

• Features: Data and parity information distributed across all disks
• Advantages: Balances performance and redundancy
• Disadvantages: Lower write performance
• Minimum Disks: 3
• Capacity Formula:

  Total Capacity = (Number of Disks - 1) × Single Disk Capacity
  

RAID 6 (Striping with Double Parity)

• Features: Uses two independent parity blocks
• Advantages: Can survive two simultaneous disk failures
• Disadvantages: Lower write performance
• Minimum Disks: 4
• Capacity Formula:

  Total Capacity = (Number of Disks - 2) × Single Disk Capacity
  

RAID 10 (RAID 1+0)

• Features: Combination of RAID 0 and RAID 1
• Advantages: Combines performance and redundancy benefits
• Disadvantages: High cost, low storage efficiency
• Minimum Disks: 4
• Capacity Formula:

  Total Capacity = (Number of Disks × Single Disk Capacity) ÷ 2
  

RAID Selection Guidelines

1. Performance Priority: Choose RAID 0
   • Suitable for temporary data or scenarios with other backup solutions
2. Data Security Priority: Choose RAID 1
   • Suitable for critical small-capacity data storage
3. Balance of Performance and Security: Choose RAID 5
   • Suitable for most enterprise storage scenarios
4. High Reliability Requirements: Choose RAID 6
   • Suitable for large capacity storage and long-term archiving
5. Critical Business Systems: Choose RAID 10
   • Suitable for scenarios requiring both high performance and reliability

Important Notes

1. RAID is not a substitute for backups
2. Use identical disk models and capacities when building RAID
3. Enterprise-grade drives provide better reliability
4. Regularly check RAID status and disk health
5. Configure appropriate spare disks for failure recovery