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EBS Volume Types

A guide to picking the right storage drive based on performance needs and cost considerations.

Key Takeaways​

The Boot Volume Constraint​

  • The Rule: Only SSD-based volumes can be used as root/boot volumes to run the operating system.
  • Allowed: gp2, gp3, io1 and io2.
  • Banned: st1 (Throughput Optimized) and sc1 (Cold HDD) cannot be used to boot an instance under any circumstances.

General Purpose SSDs: gp2 vs. gp3​

  • gp2 (Older gen): Storage size and performance are linked. If you want more IOPS, you are forced to pay for a bigger volume size (you get 3 IOPS per GB up to a max of 16,000 IOPS, you will maxed out the IOPS at 5,334 GB and above).
  • gp3 (Newer gen): Storage size and performance are decoupled. It gives you a baseline of 3,000 IOPS and 125 MB/s throughput out of the box, and you can scale those performance numbers up independently without buying more gigabytes.
  • Use Cases: Dev/test environment, virtual desktop, low-latency web server backends.

Provisioned IOPS SSDs: io1 vs io2 Block Express​

WHen gp3 isn't fast enough and you need sustained mission-critical performance:

  • The Metrics: Use these if you need more than 16,000 IOPS per volume. io1 maxes out at 64,000 IOPS, while io2 Block Express goes wild up to 256,000 IOPS with sub-millisecond latency.
  • Developer Superpower: Only the io1 and io2 families support EBS Multi-Attach (allowing the raw network rive to be hooked up to multiple Nitro instances at once).
  • Maximum Provisioned IOPS Ratio: 50 IOPS per GB for io1 and 1000 IOPS per GB for io2 Block Express.
  • Use Cases: Critical business applications, heavy write relational databases (like large PostgreSQL or MySQL setups).

EBS Volume Types SSD

Hard Disk Drives (HDDs): st1 vs sc1​

These are completely focused on Throughput (MB/s) rather than IOPS (speed of small reads/writes).

  • st1 (throughput optimized): Built for processing massive, sequential blocks of data fast.
    • Use Cases: Big data, data warehousing, MapReduce, Log processing/aggregation.
  • sc1 (cold HDD): The absolute lowest cost block storage option on AWS. Designed for data you don't touch often.
    • Use Cases: Infrequently accessed archives, cold storage backup files.

EBS Volume Types HDD

Exam Tips​

The Database Clue: If an exam question describes a high-performance database cluster running on EC2 that needs consistent, ultra-low latency and maximum storage performance, skip gp3 and look for provisioned IOPS (io1 or io2).

The Big Data Clue: If the scenario mentions streaming massive log files, running Apache Kafka/Hadoop clusters, or streaming big data processing workloads where cost efficiency for large streams matters most, look for Throughput Optimized HDD (st1).

The Cost Architecture Trap: If a question asks how a developer can increase a volume IOPS without spending money on unneeded storage space, the correct answer is to switch from gp2 to gp3, since gp3 allows independent IOPS configuration.