Planning for the MPX Cache Agents

Consider the following when you plan for MPX Cache Agents:

• On Microsoft Windows, a MPX Cache Agent can run as a service or as a console application. More than one MPX Cache Agent can be run as a service on each computer if appropriate.
• A Root MPX Cache Agent can manage only one server configuration. It uses the server configuration’s archives for file content. It accesses the configuration's database and manages its own local cache for object contents.
• Each MPX Cache Agent must be connected to a Message Broker.
• The Root MPX Cache Agent requires access to the vault for the one server configuration that it services. Consequently, it can be installed on the same computer as the StarTeam Server. Alternatively, if it can be installed on a separate computer to prevent the Root MPX Cache Agent from competing for CPU or network I/O with the corresponding server configuration. However, this requires it to access the archive files and the CacheJournal.dat through a shared network drive, so use this option only when a high-speed network file system is in place.
• Similarly, if a root MPX Cache Agent is enabled for object caching, it requires access to the server configuration's database. If it operates on a different machine than the StarTeam Server, it will need additional configuration to access the correct database.
• There is no limit to the number of MPX Cache Agents or Message Brokers that can be installed throughout an enterprise nor any limit to the number of Message Brokers within a single messaging “cloud”. Keep in mind that each MPX Cache Agent requires access to a Message Broker.
• Remote MPX Cache Agents should be installed in each geographic location that can benefit from improved file check-out performance. One approach is to install a MPX Cache Agent in each network environment in which local users can access it over a high-speed LAN. (Example: Install two Remote MPX Cache Agents at headquarters, one each for the engineering and quality assurance teams, a third Remote MPX Cache Agent at the Chicago office, and a fourth at the London office.)
• Installing a Remote MPX Cache Agent on a computer dedicated to a check-out intensive application such as a build utility can be very beneficial. If that computer is sufficiently “network-near” to the StarTeam Server’s computer, you could deploy a Root MPX Cache Agent on the build computer as long as that computer has access to the server configuration's vault. This reduces check-out demands on the StarTeam Server, but it doesn't reduce I/O to the vault.
• A Remote MPX Cache Agent can receive broadcasts and store files and objects from multiple server configurations. It stores all new files and/or objects for the specified server configurations or for the specified projects within the server configurations. However, each unique file and object is stored only once, regardless of the number of times it is used in different folders, projects, or servers. A file’s uniqueness is determined by its contents, not its name or location. An object's uniqueness is determined by distinctive object properties.
• Cached files are stored individually within a folder tree, which has a configurable root folder. They are stored in encrypted format and decrypted only “at the last moment” within the client process.
• The maximum total size of a MPX Cache Agent’s cache is configurable.
• The cache for a MPX Cache Agent does not have to be backed up and can be deleted, if necessary, when the Remote MPX Cache Agent is not running.
• Clients can be configured to use a specific MPX Cache Agent by specifying that MPX Cache Agent’s host name (or IP address) and port number. Alternatively, some clients can be configured to locate an appropriate MPX Cache Agent automatically. If multiple MPX Cache Agents are available, the client automatically chooses the “network-nearest” MPX Cache Agent. This feature keeps administrative overhead to a minimum and allows the automatic detection of new MPX Cache Agents by clients.
• You can use a single Remote MPX Cache Agent without deploying a Root MPX Cache Agent. It will receive files through MPX broadcasts. If the Message Broker is running most of the time, it will receive most files and could be useful to a person whose job is building software applications. (Without a Root MPX Cache Agent there is no file-catch-up or request forwarding.)