Client machines run the dfsd process, which initializes the Cache Manager, and the dfsbind process. You can save disk space on a client machine by storing commonly used files in the DFS filespace. You can then create symbolic links on the local disk that refer to the files in the filespace.
When the Cache Manager retrieves a requested file, it caches the data before passing it on to an application program. It does not cache the entire file; it instead caches "chunks," or pieces, of data. By default, each chunk of cached data contains 64 kilobytes of data in a disk cache or 8 kilobytes of data in a memory cache.
The dfsd process initializes the Cache Manager on a client machine by transferring configuration information into kernel memory. It also mounts the root of the global namespace (/...). You can use the options available with the command line for the dfsd process to alter the definitions for the type of cache to be used (disk or memory), total cache size, cache chunk size, the local disk directory to be used for caching, and other configuration information.
In addition, the dfsd process starts several background daemons. These daemons include one or more maintenance daemons that perform routine maintenance tasks such as garbage collection; background daemons that improve performance by performing delayed writing of updated data; token daemons that respond to token revocation requests from File Exporters; and, on the AIX operating system, I/O daemons that move data between disk and memory.
The dfsbind process resolves CDS path names and returns information about Fileset Database machines to the Cache Manager. The information allows the Cache Manager to contact the FL Server on an appropriate Fileset Database machine in the cell to determine the locations of filesets that houses data requested by users.
The dfsbind process also returns user authentication information from the Security Server to the kernel RPC Runtime of the client machine. Authentication information must be included in RPC bindings that request data from a File Server machine for a user. The Cache Manager uses the RPC bindings to access data for the user from the File Server machine.
(See Part 2 of this guide and reference for complete information about the dfsd and dfsbind commands that start the respective processes and the options available with the commands.)
Two types of files must reside on the local disk of a client machine: boot sequence files needed during reboot, and files that are useful during File Server machine outages.
During a reboot, DFS is inaccessible until the dfsd process reinitializes the Cache Manager; the dfsbind process must be running before the dfsd process can be run. Any files that are needed during reboot and prior to the start of the dfsd process must reside on the local disk. Following is a list of recommended DFS files to store on a local disk. (See your vendor's documentation for information about the files that reside on the local disk of a client machine.)
· The dcelocal/bin/dfsbind command is the start-up command for the dfsbind process.
· The dcelocal/bin/dfsd command is the start-up command for the Cache Manager.
· The dcelocal/etc/CacheInfo file is a file that specifies aspects of Cache Manager configuration.
· The dcelocal/var/adm/dfs/cache directory is a directory that contains cache-related files, such as Vn files and the CacheItems file, generated and used by the Cache Manager.
You may also want to store diagnostic and recovery files on a local disk. Certain commands in the bos and cm command suites can help users diagnose problems caused by a File Server outage. It is useful to have local disk copies of the binary files for the bos and cm suites because the File Server outage that requires their use can also make them inaccessible. In addition, you may want to keep the binaries for a text editor, such as ed or vi, on the local disk for use during outages.
Additionally, if you wish to modify the default Cache Manager preferences for accessing File Servers and FLDB machines, you can add cm setpreference commands to the machines initialization file. Doing so ensures that such preferences are loaded each time the machine is initialized. For more information about Cache Manager preferences for File Servers and FLDB machines, see the following topic.