EC2 Instance Storage

Elastic Block Store (EBS) Volume: A network drive you can attach to instances to allow them to persist data
- Data persists even after termination
- Bound to a specific AZ (volume must be snapshotted first before moving to another AZ)
- Mounted to one instance at a time
- Free tier: 30 GB of EBS storage per month (either General Purpose (SSD) or Magnetic)
- Network drives communicate to the instance via a network, there could be some latency
- Set a provisioned capacity (size in GBs and IOPS), will get billed for this provisioned capacity. The drive capacity can be increased over time
Delete on Termination attribute (EC2 --> Instances --> Storage):
- Controls EBS behaviour when an EC2 instance terminates
  - Root EBS volume is deleted by default (attribute automatically enabled)
  - Other attached EBS volumes are not deleted by default (attribute automatically disabled)
- Controllable through AWS console / CLI
- Useful scenario: Preserve root volume when instance is terminated

Create a backup of your EBS volume at a point in time (snapshot)
Recommended to detach a volume before creating a snapshot, but is not a requirement
Snapshots can be copied across AZ or Regions
EBS Snapshot Features
- EBS Snapshot Archive
  - Move a snapshot to an archive tier, 75% cheaper
  - Takes between 24 to 72 hours for restoring the archive
- Recycle Bin for EBS Snapshots
  - Setup rules to retain deleted snapshots, allows you to recover them after accidental deletion
  - Retention can be specified between 1 day to 1 year

Amazon Machine Image: A customisation of an EC2 instance (with your own software, configuration, OS, monitoring, etc.)
- All the pre-packaged software results in a faster boot / configuration time
- Region specific, can also be copied across regions
- EC2 instances can be launched from:
  - Public AMI provided from AWS
  - Your own AMI you create and maintain yourself
  - AWS Marketplace AMI made from someone else
AMI Process
- Start an EC2 instance and customise it
- Stop the instance (preserve data)
- Build an AMI (will also create an EBS snapshot)
- Launch instances from other AMIs (Application --> OS Images)
EC2 Image Builder
- Automate the creation, maintainence and testing of EC2 AMIs
- Can be run on a schedule, when packages are updated or depending on the defined specification
- Free service, only play for underlying resources
EC2 Instance Store
- High-performance hardware disk connected to EC2 storage
  - Better I/O performance
  - EC2 Instance Store lose their storage if stopped (ephemeral)
  - Good for buffer / cache / scratch data / temporary content
  - Risk of data loss if hardware fails
  - Backups and replication are your responsibility
- Alternative to network drives (EBS volumes) which have limited performance

Elastic File System: Managed NFS (network file system) that can be mounted to many Linux EC2 instances across multiple AZ
- Highly available, scalable, expensive, pay per use, no capacity planning
- Attaches via an EFS Mount Target
EFS Infrequent Access (EFS-IA): Cost-optimised storage class for files not accessed everyday
- Up to 92% lower cost compared to EFS Standard
- EFS automatically moves your files to EFS-IA based on time last accessed, which is enabled and defined with a Lifecycle Policy
- Transparent to the applications accessing EFS

AWS responsibilities:
- Infrastructure
- Replication for data for EBS volumes & EFS drives
- Replacing faulty hardware
- Ensuring their employees can't access your data
User responsibilities:
- Setting up backup / snapshot procedures
- Setting up data encryption
- Responsibility of any data on the drives
- Understanding the risk of using EC2 Instance Store