The burst balance for my Amazon Elastic Block Store (Amazon EBS) volume is low, and I don't know why.
Amazon EBS volume types that use burst performance, such as gp2, st1, and sc1, have a baseline performance depending on volume size. If your workload is driving I/O traffic to one of these volume types beyond its baseline performance, then burst credit gets spent. If your workload continues to drive I/O traffic beyond the baseline performance, then your burst credit runs low. If your burst credit reaches zero, then these volume types get throttled at their baseline IOPS or throughput. Volumes start to earn burst credits again only after the workload stops, or its activity reaches below the volume type's baseline performance.
Note: Volume type gp3 doesn't use burst performance.
For more information, see the following AWS Documentation: