Performance Analyzer is an agent and REST API that allows you to query numerous performance metrics for your cluster, including aggregations of those metrics, independent of the Java Virtual Machine (JVM). PerfTop is the default command line interface (CLI) for displaying those metrics.
PerfTop has four pre-built dashboards in the `dashboards` directory, but you can also [create your own]({{site.url}}{{site.baseurl}}/monitoring-plugins/pa/dashboards/).
You can also load the pre-built dashboards (ClusterOverview, ClusterNetworkMemoryAnalysis, ClusterThreadAnalysis, or NodeAnalysis) without the JSON files, such as `--dashboard ClusterThreadAnalysis`.
- For NodeAnalysis and similar custom dashboards, you can add the `--nodename <node_name>` argument if you want your dashboard to display metrics for only a single node.
- For troubleshooting, add the `--logfile <log-file>.txt` argument.
## Performance Analyzer configuration
### Storage
Performance Analyzer uses `/dev/shm` for temporary storage. During heavy workloads on a cluster, Performance Analyzer can use up to 1 GB of space.
Docker, however, has a default `/dev/shm` size of 64 MB. To change this value, you can use the `docker run --shm-size 1gb` flag or [a similar setting in Docker Compose](https://docs.docker.com/compose/compose-file#shm_size).
If you're not using Docker, check the size of `/dev/shm` using `df -h`. The default value is probably plenty, but if you need to change its size, add the following line to `/etc/fstab`:
Performance Analyzer supports encryption in transit for requests. It currently does *not* support client or server authentication for requests. To enable encryption in transit, edit `performance-analyzer.properties` in your `$OPENSEARCH_HOME` directory: