Chapter 15. Tuning Ambari Performance for large (>2K-node) clusters

For an HDP cluster having more than 2000 nodes, we recommend that you tune performance in the following ways:

Calculate and set a larger task cache size on the Ambari Server.
Disable Nagios macros for large clusters to reduce the time Nagios spends processing macro definitions.
Increase the maximum number of open files allowed on the Ganglia and Nagios hosts.

Calculate an appropriate cache size using the following formula:
ecCacheSizeValue = 60 * {cluster_size}, where cluster_size is the number of nodes in the cluster.
On the Ambari Server host, in /etc/ambari-server/conf/ambari-properties, add the following property and value:
```
server.ecCacheSize={ecCacheSizeValue}
```
On the Ambari Server host, disable environment macros for large clusters by making the following changes:
```
-enable_environment_macros=1
+enable_environment_macros=0
```
- For HDP2, make these changes in /var/lib/ambari-server/resources/stacks/HDP/2.0.6/services/NAGIOS/package/templates/nagios.cfg.j2
- For HDP1, make these changes in /var/lib/ambari-server/resources/stacks/HDP/1.3.2/services/NAGIOS/package/templates/nagios.cfg.j2
On Ganglia and Nagios hosts, in /etc/security/limits.conf replace the ulimit value with a higher number.
Note
Ganglia runs as user = nobody, by default. Nagios runs as user = nagios, by default.
Restart Ambari Server.
```
ambari-server restart
```
Restart Nagios.
Using Ambari Web > Services > Nagios > Service Actions, choose Restart All.

	Note
Ganglia runs as user = nobody, by default. Nagios runs as user = nagios, by default.