Although each server can be monitored individually, it is often difficult to isolate a series of logged events as they occur across a group of SharePoint servers. Adding to this complexity is the requirement for monitoring processor, memory, and I/O on the SQL data tier.
There are at least two options available which will enable you to monitor the entirety of the farm: usage and health data collection services and System Center Monitoring Pack with Systems Center 2012 Operations Manager.
The first option enables data points to be captured within the logging database, where existing views (and newly created views) can be used for analysis.
The second option enables the monitoring of a SharePoint farm (and all ...