# Amazon EBS optimization An Amazon EBS–optimized instance uses an optimized configuration stack and provides additional, dedicated capacity for Amazon EBS I/O. This optimization provides the best performance for your EBS volumes by minimizing contention between Amazon EBS I/O and other traffic from your instance. EBS–optimized instances deliver dedicated bandwidth to Amazon EBS. When attached to an EBS–optimized instance: + `io2` Block Express volumes are designed to deliver an average latency of under 500 microseconds for 16KiB I/O operations. `io2` Block Express volumes also deliver better outlier latency compared to General Purpose volumes, reducing the frequency of I/Os exceeding 800 microseconds by over 10 times. `io1` and `io2` volumes are designed to deliver at least 90% of their provisioned IOPS performance 99.9% of the time in a given year. + `gp2` and `gp3` volumes are designed to deliver at least 90% of their provisioned IOPS performance 99% of the time in a given year. + `st1` and `sc1` volumes deliver at least 90% of their expected throughput performance 99% of the time in a given year. Non-compliant periods are approximately uniformly distributed, targeting 99% of expected total throughput each hour. For more information, see [Amazon EBS volume types](ebs-volume-types.md). The I/O size of your workload will impact the observed average latency as latency increases with larger I/O size. For example, `io2` Block Express volumes are designed to deliver an average latency of under 500 microseconds for 16KiB I/O operations. For more information, see [Amazon EBS–optimized instances](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-optimized.html) in the *Amazon EC2 User Guide*.