Check manual page of ucd_mem
Total and used Memory on systems using UCD SNMP Daemon
This check monitors the available and total memory
via SNMP on systems running the UCD SNMP daemon.
This daemon is mostly found on Linux systems and used by some hardware
appliances (such as Riverbed Steelhead).
Upper default levels are set to 80, 90 %. These levels are configurable.
One service is created.