I Treated EC2 Instance Store Like EBS – That Was a Painful Mistake

🚫 My Mistake: I Thought EC2 Instance Store Was Persistent Like EBS

I was setting up a high-performance EC2 instance for a data-intensive job. I noticed that the instance came with Instance Store volumes, and I thought, “Awesome! Free fast storage!”

So I moved some logs, temporary files, and even a bit of database data onto it. All good, right? Not so fast.

One day, I stopped the instance for a configuration change, and when I restarted it — everything on the instance store was gone.

✅ What I Learned: EC2 Instance Store Is Ephemeral

Here’s the truth that hit me hard:

• EC2 Instance Store is ephemeral storage — it exists only for the lifetime of the instance.

• If the instance is stopped, terminated, or the underlying hardware fails, the data is irretrievably lost.

• It’s physically attached to the host server. Unlike EBS volumes, it cannot survive reboots or reattachments.

📌 When You Should Use EC2 Instance Store

While it's volatile, EC2 Instance Store has its use cases:

• High-speed I/O operations where persistence isn’t required.

• Caching layers that can be rebuilt.

• Temporary files or scratch space for data processing.

• Buffering before pushing to S3 or EBS.

🛑 When You Shouldn’t Use It

• For storing databases unless you’re syncing them elsewhere.

• Any critical logs, files, or app data.

• Situations where you may stop or restart your instance often.

💡 Lesson Learned

I now treat EBS as my go-to for anything that matters and use Instance Store strictly for performance-boosted, short-term tasks.

Before trusting your data to any AWS storage option, ask yourself: “Will this survive an instance stop?” If the answer is no, it’s Instance Store, and you’d better plan accordingly.