Persistent vs. Ephemeral: Choosing the Right Storage in AWS
Meet Jake, the Curious Cloud Enthusiast
Jake, our eager high school student, has been diving deeper into AWS. Today, he comes across two storage options when launching an EC2 instance: EBS (Elastic Block Store) and Instance Store. Confused, he asks his mentor, Alex, “Which one should I use, and why does it matter?”
Alex chuckles. “That depends on what you’re trying to do. Let me explain with an example.”
The Coffee Shop Analogy
“Imagine you run a coffee shop,” Alex begins. “You need a place to store your ingredients: coffee beans, milk, sugar, etc. You have two choices:
- A personal storage locker (EBS): It’s secure, always available, and retains your ingredients even if the shop closes for the night.
- A shared pantry (Instance Store): It’s fast and accessible, but when the shop closes or moves, all ingredients are gone!”
Jake’s eyes widen. “So EBS is like my personal storage that sticks around, while Instance Store is temporary?”
“Exactly! Now, let’s get into the details.”
Understanding EBS (Elastic Block Store)
Key Features:
✅ Persistent storage—data remains even if the instance stops or terminates.
✅ Available in multiple types (gp3, io1, st1, etc.) for different use cases.
✅ Can be detached from one EC2 instance and reattached to another.
✅ Supports snapshots for backups and disaster recovery.
✅ Slightly higher latency compared to Instance Store.
Best Use Cases:
✔️ Databases (MySQL, PostgreSQL)
✔️ Application servers
✔️ Critical data storage
✔️ Any workload requiring long-term persistence
Understanding Instance Store
Key Features:
✅ Super fast—directly attached to the physical hardware.
✅ No additional cost (included with EC2 instance pricing).
✅ Best for temporary or cache-like data.
✅ Data is lost when the instance stops, terminates, or crashes.
Best Use Cases:
✔️ Temporary caches and buffers
✔️ High-speed, ephemeral data processing
✔️ Distributed computing (Hadoop, Spark)
✔️ Applications that rebuild data on restart
Side-by-Side Comparison
| Feature | EBS | Instance Store |
|---|---|---|
| Persistence | ✅ Yes | ❌ No |
| Speed | 🚀 Fast | ⚡ Super Fast |
| Cost | 💰 Pay for usage | 🆓 Free (included with EC2) |
| Backup & Snapshots | ✅ Yes | ❌ No |
| Use Cases | Databases, Web Apps | Caching, Temporary Storage |
Jake grins. “So if I need something permanent, I go with EBS. But if I just need super-fast, temporary storage, I use Instance Store?”
Alex nods. “Exactly! And remember, AWS doesn’t allow snapshots for Instance Store, so back up critical data elsewhere.”
SAA Exam Practice Question
Question: You are running a real-time analytics application that processes large amounts of temporary data and does not need to persist it. Which storage option should you use?
A) Amazon EBS
B) Instance Store
C) Amazon S3
D) AWS Backup
Answer: B) Instance Store – because it provides high-speed temporary storage for ephemeral data.
Conclusion
Jake now understands the difference between EBS and Instance Store and feels ready to make the right choice for different AWS workloads. “Thanks, Alex! I can’t wait for the next lesson.”
And just like that, Jake is one step closer to mastering the AWS cloud! 🚀
Next Up: Stay tuned for our next blog post on “S3 vs. EFS vs. FSx”—Which AWS storage service should you choose?