Phase Verbs / Action Phrases
| Phrase | Meaning |
|---|---|
| attach (a drive) | connect storage to an instance |
| leverage | take advantage of / use |
| stop / terminate | shut down an EC2 instance (stop = pause; terminate = delete) |
| back it up | create a copy for safety |
| replicate | duplicate data across locations |
Technical Vocabulary
| Term | Definition |
|---|---|
| EC2 Instance Store | High-performance ephemeral disk physically attached to the host server of an EC2 instance |
| Ephemeral storage | Temporary storage — data is lost when the instance stops or terminates |
| I/O performance | Input/Output speed — how fast data can be read from or written to disk |
| IOPS | Input/Output Operations Per Second — a measure of disk speed |
| Throughput | Amount of data transferred per unit of time |
| EBS (Elastic Block Store) | Network-attached, durable block storage for EC2 (contrast with Instance Store) |
| Buffer | Temporary data area used to smooth out differences in speed between components |
| Cache | Fast-access storage layer holding frequently used data |
| Scratch data | Temporary working data that does not need to be persisted |
| Durable storage | Storage that persists data even after instance stops (e.g., EBS, S3) |
| I3 instance | EC2 instance family optimized for high I/O with NVMe instance store disks |
Key Concepts
What is EC2 Instance Store?
- A hardware disk physically attached to the server hosting your EC2 instance
- Provides much higher I/O performance than EBS (network-attached)
- Example performance: up to 3.3 million read IOPS vs. ~32,000 IOPS for EBS gp2
The Critical Caveat — Ephemeral
- If you stop or terminate the instance → storage is lost
- It is not durable — cannot be used for long-term data storage
- If the physical server fails → the instance store fails too
Good Use Cases (short-lived data only)
- Buffer / cache
- Scratch / temporary data
- High-speed intermediate computation
NOT suitable for
- Long-term storage (use EBS instead)
- Data that must survive instance stop/terminate
Your Responsibility
- If you use Instance Store, you must back it up and replicate the data
- AWS does not protect this data for you
Exam Tip
Anytime you see “very high performance hardware-attached volume for EC2” → think EC2 Instance Store