Monitor Hosts with On Prem MMS Monitoring¶

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Monitoring Architecture
Additional Considerations for MongoDB 2.4 Nodes

The Monitoring agent automatically discovers MongoDB processes based on existing cluster configuration. You’ll have to manually “seed” at least one of these hosts from the MMS console.

To add a host to On Prem MMS Monitoring, click the “plus” (+ ADD HOST) button at the top of the Hosts page. This raises a query element for the hostname, port, and optionally an admin DB username and password. Provide the necessary information and select “Add.”

Once it has a seed host, the Monitoring agent will discover any other nodes from associated clusters. These clusters, and their respective seed hosts, include:

Master databases, after adding slave databases.
Shard clusters, after adding mongos instances.
Replica sets, after adding any member of the set.

Once you add these seed nodes, the Monitoring agent will fetch this information from the MMS servers. Thus, when configuring the monitoring environment, you may need to wait for several update cycles (e.g. 5-10 minutes) to complete the auto-discovery process and host identification. During this period, you may see duplicate hosts in the MMS web console. This is normal.

The Monitoring agent fetches configuration and reports to On Prem MMS Monitoring every minute, so, again, there may be a delay of several minutes before data and host information propagate to the MMS console.

You can find immediate evidence of a working installation in the agent output or logs. For more information, check the MMS console’s “Hosts,” section in the “Agent Log” and “Pings” tabs. Once On Prem MMS Monitoring has data, you can view and begin using the statistics.

If the agent cannot collect information about a host for 24 hours, the On Prem MMS Monitoring system deactivates the instance in the Monitoring agent and console. Deactivated hosts must be manually reactivated from the MMS console if you wish to collect data from these hosts.

Monitoring Architecture¶

Only one Monitoring agent per group or environment will report to On Prem MMS Monitoring at a time. However, you can run multiple instances of the agent to provide redundancy. Secondary agents act as hot standbys. If you stop the agent process, On Prem MMS Monitoring removes the agent from the “Agents” tab within a day. If a Monitoring agent is unavailable, the last ping times for that agent do not update. To install secondary agents, simply repeat the installation process in the installation guide for each new agent. You can also automate agent installation.

Note

When the Monitoring agent restarts, there is a five minute delay before that agent begins collecting data sending pings to On Prem MMS Monitoring. If you have multiple agents, this delay permits other agents in your infrastructure to become the “primary agent” and for On Prem MMS Monitoring to determine which agent will be primary.

During this interval, the restarted Monitoring agent will not collect data.

Additional Considerations for MongoDB 2.4 Nodes¶

If you are monitoring a MongoDB 2.4 instance with authentication enabled, you must have elevated privileges to collect complete performance data. At a minimum, the user will need to possess:

the clusterAdmin role, and
the readAnyDatabase role.

If MMS is running with DB Profiling enabled, the user requires additional permissions. In addition to the clusterAdmin and readAnyDatabase roles, the user must possess either:

the dbAdminAnyDatabase role, or
the dbAdmin role on the specific databases being profiled.

However, if you do not have DB Profiling enabled and you are not collecting dbStats data, the agent only needs permissions provided by the clusterAdmin role.