RAC processes

LMON: Lock Monitor Process

LMON maintains GCS memory structures. It handles the abnormal termination of processes and instances. Reconfiguration of locks and resources when an instance joins or leaves the cluster are handled by LMON. Activities that occur during instance reconfigurations are tracked by it in its trace file. In versions 10gR2 and later, LMON is responsible for executing dynamic lock remastering every 10 minutes. In current versions, LMON is known as the Global Enqeueue Services monitor.

LMS: Lock Manager Server

LMS is the most active Oracle RAC background process; it can become very active, consuming significant amounts of CPU time. Oracle recommends that this process be allocated the needed CPU time by increasing its priority. Starting from 10g R2, Oracle has implemented a feature to ensure that the LMS process does not encounter CPU starvation. It is also known as the Global Cache Service (GCS) process in current versions.