Glossary · Storage
What are EBS Volume Types?
The performance / cost tiers of Amazon Elastic Block Store — gp3 (default modern general-purpose), gp2 (legacy), io2 (provisioned IOPS), st1 / sc1 (throughput / cold HDD).
By HabileLabs
EBS Volume Types
EBS volume types control the price-performance curve for block storage attached to EC2:
- gp3 — modern general-purpose SSD, default for new EC2. 3,000 IOPS / 125 MB/s baseline. ~20% cheaper than gp2 at equivalent size.
- gp2 — legacy general-purpose SSD. IOPS scale with size (3 per GB). Default before 2020. Migrate to gp3 unless you need the burst credits.
- io2 / io2 Block Express — provisioned IOPS SSD for the most demanding databases. Expensive but predictable.
- st1 / sc1 — HDD-backed throughput-optimized / cold storage. Cheap per GB but high latency. Best for large sequential workloads like log aggregation, big-data scratch space.
The single most common EBS waste mode is fleets still running on gp2 when gp3 has been the better choice for years. Migration is in-place and zero-downtime — just an API call (modify-volume) — and yields ~20% savings without any application change.
Other waste modes: oversized provisioned IOPS on io2 volumes, orphaned snapshots (snapshots of long-deleted volumes), and unattached volumes left over from terminated instances.
- !gp2 → gp3 migration must wait until the volume's previous modification is complete (often a 6-hour cooldown).
- !Snapshot copies in other regions incur cross-region transfer cost — lifecycle aggressively.
- !Even unattached EBS volumes are billed at the full volume rate.
Related
Idle Resource
An AWS resource that is provisioned and billed but doing no real work — common offenders: unattached EBS volumes, idle EC2, unused elastic IPs, abandoned load balancers.
Right-sizing
Matching the instance type and size to actual workload demand — avoiding both over-provisioning (paying for idle capacity) and under-provisioning (performance pain).
Cost Optimization
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