Instance Storage

Instance storage in AWS (also called ephemeral storage) is physical disk storage that's directly attached to the host EC2 instance. It is categorized as "block-level storage" that comes directly attached to EC2 instances.

Here are its key characteristics:

1. It's temporary - all data is lost when the instance stops or terminates (data persists during reboots)

2. Provides very high IOPS and lowest latency since it's physically attached to the host

3. Included in the instance price with no additional cost

4. Size is fixed based on the instance type

5. Ideal for temporary storage needs like:

   • Cache data

   • Scratch space

   • Buffer/queue data

   • Temporary processing files

Not all instance types come with instance storage, and you can't add it after launching an instance. For persistent storage needs, EBS volumes are recommended instead.

Features	Instance Store	EBS Volumes
Persistence	Temporary (lost on stop/termination)	Persistent (independent of instance)
Latency	Lowest (physically attached)	Low (network attached)
IOPS	Very high (depends on instance type)	Up to 256,000 (io2 Block Express)
Use Cases	Temporary storage, cache, scratch data	Persistent data, databases, boot volumes
Backup	Manual only	Snapshots available
Size Limits	Fixed by instance type	Up to 16 TiB per volume
Availability	Not all instance types	All instance types
Data Redundancy	None (single disk failure = data loss)	Replicated within AZ
Cost	Included in instance price	Additional cost per GB-month
Performance	Consistent high performance	Varies by volume type