Comparing EBS vs Instance Store
Definition
Amazon EBS (Elastic Block Storage)
EBS is a network-attached, persistent block storage service designed to be used with EC2 instances.
Volumes persist independently of the EC2 instance
Can be attached, detached, and reattached to instances
EBS is commonly used for:
Boot volumes
Databases
Long-lived application data
Instance Store
Instance Store is ephemeral, physically attached storage that comes with certain EC2 instance types.
Storage is local to the host machine
Provides extremely high I/O performance
Data is lost when instance stops, terminates, or fails
Instance Store is commonly used for:
Temporary data
Caches
Buffers
Trade-offs
Choose EBS for persistence and Instance Store for performance
| Aspect | EBS | Instance Store |
| Storage type | Network attached | Local to host |
| Persistence | Persistent | Ephemeral |
| Durability | Replicated within AZ | None |
| Latency | Low milliseconds | Microseconds |
| Max IOPS | High | Very high |
| Data survival | Survives instance stop | Lost on stop/terminate |
| Cost model | Pay per GB / IOPS | Included with instance |
Scenarios
| Scenario | Use EBS | Use Instance Store |
| Data must persist | ✅ Yes | ❌ No |
| Ultra-low latency required | ❌ No | ✅ Yes |
| Highest possible I/O | ❌ No | ✅ Yes |
| Backups / snapshots needed | ✅ Yes | ❌ No |
| Instance may stop / start | ✅ Yes | ❌ No |
| Temporary or reproducible data | ❌ No | ✅ Yes |
| Databases | ✅ Yes | ❌ No |
| Caches / scratch space | ❌ No | ✅ Yes |
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