| Configuration and Cache-Related Files on the Local Disk | ||
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 | Chapter 10. Administering Client Machines and the Cache Manager |  |
| Configuration and Cache-Related Files on the Local Disk | ||
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| | Chapter 10. Administering Client Machines and the Cache Manager | |
This section briefly describes the client configuration files that must reside in the local /usr/vice/etc directory on every client machine. If the machine uses a disk cache, there must be a partition devoted to cache files; by convention, it is mounted at the /usr/vice/cache directory.
Note for Windows users: Some files described in this document possibly do not exist on machines that run a Windows operating system. Also, Windows uses a backslash (\) rather than a forward slash (/) to separate the elements in a pathname.
The /usr/vice/etc directory on a client machine's local disk must contain certain configuration files for the Cache Manager to function properly. They control the most basic aspects of Cache Manager configuration.
If it is important that the client machines in your cell perform uniformly, it is most efficient to update these files from a central source. The following descriptions include pointers to sections that discuss how best to maintain the files.
The binary file for the program that initializes the Cache Manager. It must run each time the machine reboots in order for the machine to remain an AFS client machine. The program also initializes several daemons that improve Cache Manager functioning, such as the process that handles callbacks.
A one-line file that sets the cache's most basic configuration parameters: the local directory at which the Cache Manager mounts the AFS filespace, the local disk directory to use as the cache, and how many kilobytes to allocate to the cache.
The OpenAFS Quick Beginnings explains how to create this file as you install a client machine. To change the cache size on a machine that uses a memory cache, edit the file and reboot the machine. On a machine that uses a disk cache, you can change the cache size without rebooting by issuing the fs setcachesize command. For instructions, see Determining the Cache Type, Size, and Location.
This ASCII file names the database server machines in the local cell and in any foreign cell to which you want to enable access from this machine. (Database server machines are the machines in a cell that run the Authentication, Backup, Protection, and VL Server processes; see Database Server Machines.)
The Cache Manager must be able to reach a cell's database server machines to fetch files from its filespace. Incorrect or missing information in the CellServDB file can slow or completely block access. It is important to update the file whenever a cell's database server machines change.
As the afsd program initializes the Cache Manager, it loads the contents of the file into kernel memory. The Cache Manager does not read the file between reboots, so to incorporate changes to the file into kernel memory, you must reboot the machine. Alternatively, you can issue the fs newcell command to insert the changes directly into kernel memory without changing the file. It can also be convenient to upgrade the file from a central source. For instructions, see Maintaining Knowledge of Database Server Machines.
(The CellServDB file on client machines is not the same as the one kept in the /usr/afs/etc directory on server machines, which lists only the local cell's database server machines. For instructions on maintaining the server CellServDB file, see Maintaining the Server CellServDB File).
This optional ASCII file lists one or more of the network interface addresses on the client machine. If it exists when the Cache Manager initializes, the Cache Manager uses it as the basis for the list of interfaces that it registers with File Servers. See Managing Multihomed Client Machines.
This optional ASCII file lists one or more network interface addresses. If it exists when the Cache Manager initializes, the Cache Manager removes the specified addresses from the list of interfaces that it registers with File Servers. See Managing Multihomed Client Machines.
This ASCII file contains a single line that specifies the complete domain-style name of the cell to which the
machine belongs. Examples are example.com and
example.org. This value defines the default cell in which the machine's users become
authenticated, and in which the command interpreters (for example, the bos command)
contact server processes.
The OpenAFS Quick Beginnings explains how to create this file as you install the AFS client functionality. To learn about changing a client machine's cell membership, see Setting a Client Machine's Cell Membership.
In addition to these files, the /usr/vice/etc directory also sometimes contains the following types of files and subdirectories:
The AFS initialization script, called afs.rc on many system types. In the conventional configuration specified by the OpenAFS Quick Beginnings, it is a symbolic link to the actual script kept in the same directory as other initialization files used by the operating system.
A subdirectory that houses AFS kernel library files used by a dynamic kernel loading program.
A subdirectory called C, which houses the Cache Manager catalog file called afszcm.cat. The fstrace program uses the catalog file to translate operation codes into character strings, which makes the message in the trace log more readable. See About the fstrace Command Suite.
A client machine that uses a disk cache must have a local disk directory devoted to the cache. The conventional mount point is /usr/vice/cache, but you can use another partition that has more available space.
Do not delete or directly modify any of the files in the cache directory. Doing so can cause a kernel panic, from which the only way to recover is to reboot the machine. By default, only the local superuser root can read the files directly, by virtue of owning them.
A client machine that uses a memory cache keeps all of the information stored in these files in machine memory instead.
A binary-format file in which the Cache Manager tracks the contents of cache chunks (the V files in the directory, described just following), including the file ID number (fID) and the data version number.
A binary-format file in which the Cache Manager records the mapping between mount points and the volumes from which it has fetched data. The Cache Manager uses the information when responding to the pwd command, among others.
A cache chunk file, which expands to a maximum size (by default, 64 KB) to house data fetched from AFS files. The number of Vn files in the cache depends on the cache size among other factors. The n is the index assigned to each file; they are numbered sequentially, but the Cache Manager does not necessarily use them in order or contiguously. If an AFS file is larger than the maximum size for Vn files, the Cache Manager divides it across multiple Vn files.
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| Overview of Cache Manager Customization |  | Determining the Cache Type, Size, and Location |