A TREX instance is an administrative unit that comprises the TREX server components. A TREX instance is started and stopped as a unit.
The following components belong to a TREX instance.
A name server
A queue server
One or more index servers
One or more preprocessors
Optionally, one or more RFC servers
Optionally, one or more Web servers
A TREX instance runs on a host. It is possible for several TREX instances to run on the same host. A TREX instance is identified by a two-character instance number. This instance number must be unique on a host.
A TREX system consists of one or more TREX instances. If it consists of only one TREX instance, it is called a single host system. If it consists of multiple connected TREX instances, it is called a distributed system.