Cloudability’s Rightsizing feature ranks your resources by Priority, a cost-weighted, normalized score incorporating both utilization and cost metrics. This score takes into account a number of standard utilization metrics such as disk I/O, CPU, and network utilization -- all coming from the CloudWatch API. To improve the Rightsizing priority score and provide more context to rightsizing activities, we suggest you include memory utilization metrics. AWS does not provide a standard CloudWatch metric for memory utilization so it is necessary to install a script on each host to gather this data.
This document will walk you through setting up a script to gather host-level memory metrics via AWS CloudWatch. This script is only supported for Amazon EC2 instances running Linux.
Full instructions are available on the AWS site -- it is recommended to follow those instructions to set up the script.
The script monitors both disk and memory usage. At a minimum you need to install the mon-put-instance-data.pl script with the --mem-util flag on for each EC2 Linux instance you want to measure.
This will report memory utilization as a custom metric named "System/Linux MemoryUtilization", which the Cloudability platform will ingest.
After this is complete, Cloudability will ingest the metric and update its rightsizing calculations every few hours. You will start seeing memory utilization in our platform within 24 hours. The following screenshot illustrates the Rightsizing feature being properly used (green box) versus not configured (red box). Again, it is possible to use the Rightsizing feature without memory configured but you will realize better recommendations and context with memory properly ingested.