EBS vs Instance storage

Question 1

When should you use EBS by default over Instance storage?

Answer 1

If the read/write can be handled by EBS, that should be the default.

Question 2

When should you use EBS over instance storage?

Answer 2

• Highly available and reliable in an AZ. Can self-correct against HW issues on the physical hardware.
  
  • Data will be impacted only in the case that the whole AZ fails.
• Persist independently from EC2 instances.
  
  • Volumes can be created independently of EC2 instances
  • Volumes can be removed or reattached.
  • You can terminate the instance and keep the data.
• Clusters - multi-attach feature of io1
  
  • Can create a multi shared volume.
• Region resilient by using backups - snapshots.
• EXAM: Require up to 64,000 IOPS and 1,000 MiB/s per volume
• EXAM: Require up to 80,000 IOPS and 2,375 MB/s per instance

Question 3

When should you use Instance storage over EBS?

Answer 3

• Great value, they’re included in the cost of an instance.
• More than 80,000 IOPS and 2,375 MB/s - because it is local
• If you need temporary storage, or can handle volatility.
• Stateless services, where the server holds nothing of value - webservers, data manipulation apps, media processing…
• Useful for caching, temporary areas of DBs
• Rigid lifecycle link between storage and the instance.
  
  • This ensures the data is erased when the instance goes down.
• Anything temporary

Question 4

What is the current performance cap for EBS?

Answer 4

80,000 IOPS and 2,375 MB/s