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The TREX server software comprises two parts:

  • TREX Instances

    These are the program files, configuration files, and so on.

  • Global file system

    This is a directory structure, in which information about the TREX system instances is stored. For example, this information is required by management tools to start the TREX system.

    There is exactly one global file system for a TREX system. When a TREX instance starts, it must have access to the global TREX file system. Otherwise, it cannot start. The global file system consists of the SAP system directory usr/sap/<sapsid>/sys.


    In the TREX 7.1 installation, the global file system function is available in restricted form only. The customer can no longer specify the path to the global file system during the installation process (SAP system directory usr/sap/<sid>/sys). The global file system is installed once only, on the host on which you initially install TREX 7.1 and it cannot be installed again independent of this. Therefore, there is still a global file system in the TREX 7.1 installation, but it cannot be installed on another host in the TREX landscape independent of the initial TREX 7.1 installation. TREX is developing the unrestricted global file system feature in TREX 7.1 for the end of 2008.

When planning a distributed TREX system, you must decide which host the global TREX file system should be located on. This determines the installation steps that you work through later and which installation option you choose respectively. The following installation options are available:

Installation Option


TREX system

Installing a combination of a TREX instance and a global TREX file system

TREX instance

Install the TREX instance only

The global file system can be located on any host as long as all TREX instances have access to it when they start.


SAP recommends the following for a distributed TREX system with centralized data storage:

Place the global file system on the file server that the TREX data (indexes, queues, snapshots) is also stored on.

In order to serve as data storage, the file server and the connection between the TREX hosts and the file server must be highly available. If the global file system is also located on the file server, you can be sure that the TREX instances can access it at all times.

For the installation process this means that you install the global TREX file system on the file server. You install a TREX instance on every master host, backup host, and slave host.

SAP recommends the following for a distributed TREX system with decentralized data storage:

Place the global TREX file system on a host that is used as the master name server.

For the installation process, this means that you install a TREX system on the host that is used as the master name server (TREX instance together with the global file system). On all other hosts, you install TREX instances.

The graphic below depicts such a scenario.