EBS Multi-Attach

• Feature: Allows a single EBS volume (io1 or io2) to be attached to multiple EC2 instances within the same Availability Zone.
• Benefits:
  • Simultaneous read/write access from all attached instances.
  • Increased application availability for clustered setups.
  • Supports applications requiring concurrent write operations.

Use Cases

• High Availability Clustered Applications: Ensures continued operation even if an instance fails (e.g., Teradata database).
• Applications with Concurrent Writes: Facilitates scenarios where multiple sources need to modify the shared data simultaneously.

Key Limitations

• Availability Zone Restriction: Volumes cannot be multi-attached across AZs.
• Instance Limit: Up to 16 EC2 instances can concurrently attach to a single volume.
• Cluster-Aware File System: Required to avoid data corruption from simultaneous access (not standard file systems like XFS or EXT4).

Important Notes

• Exam Tip: Remember the 16-instance limit.
• Windows Support: Cluster-aware file systems exist for Windows (e.g., CSVFS)