LearnGlossary

What is an EBS-optimized instance?

Updated 26 October 2026 · Published by Zoorik

An EBS-optimized instance is an Amazon EC2 instance, usually a virtual machine (VM), with its own bandwidth for Amazon Elastic Block Store (EBS). That’s the EBS-optimized meaning: EBS traffic gets bandwidth no other traffic can use.

EBS-optimized instance types

Instance types fall into three groups:

  • Most current generation types are EBS-optimized by default, at no extra cost.
  • Some previous generation types, such as m3.xlarge, offer it for an extra hourly fee.
  • Others, such as t2.micro and c3.8xlarge, don’t offer it.

An example

Each AWS EBS-optimized instance type has its own EBS limits. An m6i.large has these, in input/output operations per second (IOPS) for 16 KiB operations:

  • 3,600 IOPS at baseline, always.
  • 40,000 IOPS at most, for 30 minutes at least once every 24 hours.

You get the smaller of the instance’s limit and your volumes’ combined limit, whatever the volume type. Say you set its gp3 volume to 10,000 IOPS. After those 30 minutes, you get 3,600 at most.

After 30 minutes, an m6i.large limits a 10,000 IOPS volume to 3,600 One gp3 volume set to 10,000 IOPS, on an m6i.large, with 16 KiB operations. Two bars on one shared scale from 0 to 10,000 IOPS, with a column labelled you get. For 30 minutes the instance limit is 40,000 IOPS, so the violet bar fills the whole scale and you get 10,000 IOPS. After 30 minutes the instance limit is 3,600 IOPS, marked by a navy dashed line. The violet bar stops there and you get 3,600 IOPS. The other 6,400 IOPS, drawn in amber, are labelled paid for, not reached. After 30 minutes, an m6i.large limits a 10,000 IOPS volume to 3,600 One gp3 volume set to 10,000 IOPS, on an m6i.large, with 16 KiB operationsYou getFor 30 minutesinstance limit 40,00010,000 IOPSAfter 30 minutesinstance limit 3,600Paid for, not reached6,400 IOPS3,600 IOPS02,0004,0006,0008,00010,000IOPS
An illustration of the page’s example, built from AWS’s published m6i.large limits: for 30 minutes the volume’s own 10,000 IOPS is the smaller limit, after that the instance’s 3,600 IOPS baseline (the navy dashed line) is, and the other 6,400 IOPS are set and paid for but not reached, since gp3 includes only 3,000.

Why it matters for your cloud cost

  • On some previous generation types, EBS optimization adds an hourly fee.
  • gp3 includes 3,000 IOPS and 125 MiB/s of throughput. More costs extra.
  • Buy IOPS above the instance’s baseline, and you pay for speed it can’t hold.

Amoeba moves a VM’s data disks onto one pool sized to your data, then rightsizes it autonomously. Amoeba sizes its pool’s performance for 1.3 times the measured p99, within the instance’s EBS limits.

Here, p99 is the level that 99 in 100 readings stay at or below.

The free assessment works out your own figure.

Read next: io2 vs gp3: when Provisioned IOPS is worth the price

Sources: AWS, “Amazon EBS-optimized instance types” (opens in a new tab); AWS, “Specifications for Amazon EC2 general purpose instances” (opens in a new tab); AWS, “EC2 On-Demand Instance Pricing” (opens in a new tab); AWS, “Amazon EBS General Purpose SSD volumes” (opens in a new tab).

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