AWS i4i vs i3 cost: newer storage-optimized instances, better value

Quick answer

i4i is the newer storage-optimized generation, with faster NVMe local storage and better price-performance than i3. For high-IOPS, low-latency local-disk workloads (NoSQL databases, search, high-throughput transactional systems), i4i typically delivers more IOPS and throughput per dollar, so the newer generation is usually the cost-effective choice. Match the storage capacity and IOPS to real need to avoid over-provisioning.

Storage-optimized instances provide fast, local NVMe storage for workloads that need high IOPS and low latency directly attached, rather than over the network like EBS. i3 was the established generation; i4i is newer, with faster storage and better price-performance, so for suitable workloads it is usually the better-value choice.

i4i's generational improvement

i4i offers higher storage performance (more IOPS and throughput) and generally better price-performance than i3, thanks to newer NVMe storage and processors. For a workload bound by local-storage performance, i4i can deliver the same or better performance on a smaller or comparably-priced instance, which is where the saving comes from.

When storage-optimized instances fit

Workload	Why storage optimized
NoSQL databases (Cassandra, etc.)	High IOPS local storage
Search and analytics engines	Fast local scans
High-throughput transactional systems	Low-latency disk

These instances suit workloads that genuinely need fast local disk. If your workload does not, a general-purpose or compute-optimized instance with EBS is cheaper, since you are not paying for expensive local NVMe you will not use, the family-matching point from the instance families guide.

The local-storage caveat

Local NVMe storage is ephemeral, it is lost if the instance stops or fails, so these instances suit data that is replicated (across a database cluster) or regenerable, not a single durable copy. Factor replication into the design and cost, since a storage-optimized cluster needs multiple nodes for durability.

Choosing between i4i and i3

For new deployments needing storage-optimized instances, prefer i4i for its better price-performance unless a specific reason favors i3. Right-size to the storage capacity and IOPS the workload actually needs rather than the largest available, and confirm the workload truly needs local NVMe before choosing a storage-optimized family at all. The generational upgrade is usually free value, the same reasoning as any newer-generation move.

FAQ

Is i4i cheaper than i3?

i4i offers better price-performance than i3, with faster NVMe storage and newer processors, so for a storage-bound workload it typically delivers the same or better performance on a smaller or comparably-priced instance. The newer generation is usually the more cost-effective choice for high-IOPS local-storage workloads.

When should I use storage-optimized instances?

For workloads that need high IOPS and low-latency local disk: NoSQL databases like Cassandra, search and analytics engines that scan locally, and high-throughput transactional systems. If the workload does not need fast local disk, a general-purpose instance with EBS is cheaper.

What is the caveat with local NVMe storage?

It is ephemeral, lost if the instance stops or fails, so it suits data that is replicated across a cluster or regenerable, not a single durable copy. Factor replication into the design and cost, since a storage-optimized deployment typically needs multiple nodes for durability.

Should I choose i4i or i3 for a new deployment?

Prefer i4i for its better price-performance unless a specific reason favors i3. Right-size to the storage capacity and IOPS the workload actually needs, and first confirm the workload truly requires local NVMe before choosing a storage-optimized family at all.

Are storage-optimized instances worth the cost?

For workloads genuinely bound by local-storage performance, yes, since they provide IOPS and latency that network-attached EBS cannot match cheaply. For workloads that do not need fast local disk, they over-pay for capability you will not use, so match the family to the real bottleneck.

Does C3X estimate storage-optimized instance cost?

C3X prices i4i, i3, and other storage-optimized instances from your Terraform, so you can compare generations for the same workload before deploy. Whether you need local NVMe, and how much replication the design requires, are architecture questions you assess separately.

What to do next

Compare storage-optimized generations before you deploy. C3X reads your Terraform and prices your resources against a live catalog. Start with the quickstart.