# Elastic File System (EFS)
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## Percent of I/O utilization
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+ The alarm changes state if the I/O utilization is consistently equal to or greater than 100% for 1 minute, indicating the need for additional capacity.
+ The alarm returns to the `OK` state if the I/O utilization is within the acceptable threshold for 5 minutes.
+ If this metric is at 100% often, then consider moving the application to an EFS using the Max I/O performance mode.
+ Metric: `PercentIOLimit` > 100%