How RAID 1 (Mirroring) Works: Benefits and Limitations

RAID 1 (Mirroring) works by duplicating data exactly on two or more drives, creating an identical copy on each drive. This means every write operation is performed on all drives simultaneously, ensuring that if one drive fails, the other(s) still have the complete data, allowing the system to continue operating without data loss.

Benefits of RAID 1:

• High fault tolerance and data redundancy: Since data is mirrored, the system can survive a single drive failure without losing data or downtime.
• Improved read performance: Read operations can be faster because data can be read from any of the mirrored drives, enabling parallel read access.
• Instant failover: If one drive fails, the RAID controller switches to the other drive immediately, supporting continuous operation and easy recovery.
• Simple data protection: RAID 1 is straightforward to implement and provides reliable protection for critical data, making it suitable for databases and financial records.

Limitations of RAID 1:

• Storage efficiency is halved: Because data is duplicated, usable storage capacity is only 50% of the total raw capacity. For example, two 1 TB drives provide only 1 TB of usable space.
• Write performance can be slower: Writing data to multiple drives simultaneously can reduce write speed, although some RAID controllers mitigate this issue.
• Cost: Requires twice the number of drives to store the same amount of data compared to a single disk, increasing hardware costs.
• Protection limited to hardware failure: RAID 1 protects against drive failure but does not protect against data corruption, accidental deletion, or disasters affecting all drives simultaneously.

RAID 1 is ideal for scenarios where data integrity and availability are critical and read performance is important, but it is less efficient for large-scale storage or write-intensive applications. For higher performance or capacity efficiency, other RAID levels like RAID 10 or parity-based RAID arrays may be more suitable.