Phase Verbs / Action Phrases
| Phrase | Meaning |
|---|---|
| attach (to multiple instances) | connect the same EBS volume to more than one EC2 instance |
| manage (concurrent writes) | application logic handles simultaneous write operations from multiple instances |
| enable (Multi-Attach) | activate the feature on an io1/io2 volume |
Technical Vocabulary
| Term | Definition |
|---|---|
| Multi-Attach | EBS feature allowing one volume to be attached to multiple EC2 instances concurrently |
| io1 / io2 | Provisioned IOPS SSD volume types; the only types that support Multi-Attach |
| Cluster-aware file system | File system designed for concurrent multi-node access (e.g., GFS2); required for Multi-Attach |
| Teradata | An example of a clustered application that can use Multi-Attach |
| XFS / ext4 | Standard Linux file systems that are NOT cluster-aware; cannot be used with Multi-Attach |
Key Concepts
What is Multi-Attach?
- Attach the same io1 or io2 EBS volume to multiple EC2 instances at the same time
- All attached instances get full read and write access simultaneously
Key Constraints
| Constraint | Detail |
|---|---|
| Volume type | Only io1 and io2 (not gp2, gp3, st1, sc1) |
| AZ scope | All instances must be in the same AZ — cannot span AZs |
| Max instances | 16 EC2 instances at a time |
| File system | Must be cluster-aware (not XFS/ext4) |
Use Cases
- Clustered Linux applications with high availability requirements (e.g., Teradata)
- Applications that must manage concurrent write operations themselves
- Scenarios needing shared block storage across multiple nodes in the same AZ
Exam Tips
- Multi-Attach = only for io1 or io2 volumes
- Max 16 instances can attach the same volume concurrently
- Must use a cluster-aware file system (not standard Linux filesystems)
- Same AZ only — cannot attach across AZs
- All instances have full read + write — application must handle write conflicts