What is Amazon EC2 Elastic Block Storage (EBS)?

Amazon Elastic Block Storage (EBS)

• off-instance NAS (Network Attached Storage)
• size between 1GB to 1TB, allocated in 1GB increments
• 1 EBS can only be attached to 1 EC2 instance
• 1 EC2 instance can attach multiple EBS
• for data that changes quickly and requires long-term persistance (ex. file system, database) 
• EBS volumes with less than 20GB of modified data since the last snapshot are designed for between 99.5% - 99.9% annual durability
• snapshots are available across availability zone
• if an availability zone is unavailable, the EBS will not be available
• **snapshot EBS frequently
• EBS is priced per GB-month of provisioned storage and per million I/O requests
• EBS Snapshots are priced per GB-month of data stored, as well as per 1,000 PUT requests and per 10,000 GET requests when saving and loading snapshots

How to increase/decrease size of a EBS

• Quiesce the application or file system.
• Snapshot your EBS volume’s data into Amazon S3 (using “Create Snapshot from Volume”).
• Create a new EBS volume from the snapshot, but specify a larger size than the original volume.
• Attach the new, larger volume to your Amazon EC2 instance.
• Detach and delete the original EBS volume.

Anti-Patterns

Temporary storage - use local (Ephemeral) volume

Highly-durable storage - S3 standard storage is designed for 99.999999999% annual durability per object

Static data or web content - use S3

Key-value pair, schema-less data - use SimpleDB