# Measuring Performance Between Your Application and Gateway
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Data throughput, data latency, and operations per second are three measures that you can use to understand how your application storage that is using your gateway is performing. When you use the correct aggregation statistic, you can use Storage Gateway metrics to measure these values. 

A *statistic* is an aggregation of a metric over a specified period of time. When you view the values of a metric in CloudWatch, use the `Average` statistic for data latency (milliseconds), use the `Sum` statistic for data throughput (bytes per second), and use the `Samples` statistic for input/output operations per second (IOPS). For more information, see [Statistics](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch_concepts.html#Statistic) in the *Amazon CloudWatch User Guide*.

The following table summarizes the metrics and corresponding statistic you can use to measure the throughput, latency, and IOPS between your applications and gateways. 


| Item of Interest | How to Measure | 
| --- | --- | 
| Throughput  |  Use the `ReadBytes` and `WriteBytes` metrics with the `Sum` CloudWatch statistic. For example, the `Sum` value of the `ReadBytes` metric over a sample period of 5 minutes divided by 300 seconds gives you the throughput as a rate in bytes per second.  | 
| Latency | Use the ReadTime and WriteTime metrics with the Average CloudWatch statistic. For example, the Average value of the ReadTime metric gives you the latency per operation over the sample period of time. | 
| IOPS | Use the ReadBytes and WriteBytes metrics with the Samples CloudWatch statistic. For example, the Samples value of the ReadBytes metric over a sample period of 5 minutes divided by 300 seconds gives you IOPS. | 

For the average latency graphs and average size graphs, the average is calculated over the total number of operations (read or write, whichever is applicable to the graph) that completed during the period. 

**To measure the data throughput from an application to a volume**

1. Open the CloudWatch console at [https://console.aws.amazon.com/cloudwatch/](https://console.aws.amazon.com/cloudwatch/).

1. Choose **Metrics**, then choose the **All metrics** tab and then choose **Storage Gateway**.

1. Choose the **Volume metrics** dimension, and find the volume that you want to work with.

1. Choose the `ReadBytes` and `WriteBytes` metrics.

1. For **Time Range**, choose a value.

1. Choose the `Sum` statistic.

1. For **Period**, choose a value of 5 minutes or greater.

1. In the resulting time-ordered sets of data points (one for `ReadBytes` and one for `WriteBytes`), divide each data point by the period (in seconds) to get the throughput at the sample point. The total throughput is the sum of the throughputs.

For example, if the read throughput is 2,384,199,680 bytes over a period of 300 seconds, then the approximate throughput rate for that datapoint is 7.9 megabytes per second.

**To measure the data input/output operations per second from an application to a volume**

1. Open the CloudWatch console at [https://console.aws.amazon.com/cloudwatch/](https://console.aws.amazon.com/cloudwatch/).

1. Choose **Metrics**, then choose the **All metrics** tab and then choose **Storage Gateway**.

1. Choose the **Volume metrics** dimension, and find the volume that you want to work with.

1. Choose the `ReadBytes` and `WriteBytes` metrics.

1. For **Time Range**, choose a value.

1. Choose the `Samples` statistic.

1. For **Period**, choose a value of 5 minutes or greater.

1. In the resulting time-ordered sets of data points (one for `ReadBytes` and one for `WriteBytes`), divide each data point by the period (in seconds) to get IOPS.

For example, if the number of write operations is 24,373 over a period of 300 seconds, then the IOPS for that data point is 81 write operations per second.