AMD(8) AMD(8)
NAME
amd - automatically mount file systems
SYNOPSIS
amd -H amd [ -F conf_file ] amd [ -nprvHS ] [ -a mount_point ] [ -c duration ] [ -d domain ] [ -k kernel-arch ] [ -l logfile ] [ -o op_sys_ver ] [ -t interval.interval ] [ -w interval ] [ -x log-option ] [ -y YP-domain ] [ -C cluster-name ] [ -D option ] [ -F conf_file ] [ -O op_sys_name ] [ -T tag ] [ directory map- name [ -map-options ] ] ...
DESCRIPTION
Amd is a daemon that automatically mounts filesystems whenever a file or directory within that filesystem is accessed. Filesystems are automatically unmounted when they appear to have become quiescent. Amd operates by attaching itself as an NFS server to each of the specified directories. Lookups within the speci- fied directories are handled by amd, which uses the map defined by mapname to determine how to resolve the lookup. Generally, this will be a host name, some filesystem information and some mount options for the given filesys- tem. In the first form depicted above, amd will print a short help string. In the second form, if no options are speci- fied, or the -F is used, amd will read configuration parameters from the file conf_file which defaults to /etc/amd.conf. The last form is described below.
OPTIONS
-a temporary-directory Specify an alternative location for the real mount points. The default is /a. -c duration Specify a duration, in seconds, that a looked up name remains cached when not in use. The default is 5 minutes. -d domain Specify the local domain name. If this option is not given the domain name is determined from the hostname. -k kernel-arch Specifies the kernel architecture. This is used solely to set the ${karch} selector. 3 November 1989 1 AMD(8) AMD(8) -l logfile Specify a logfile in which to record mount and unmount events. If logfile is the string syslog then the log messages will be sent to the system log daemon by syslog(3). The default syslog facil- ity used is LOG_DAEMON. If you wish to change it, append its name to the log file name, delimited by a single colon. For example, if logfile is the string syslog:local7 then Amd will log messages via syslog(3) using the LOG_LOCAL7 facility (if it exists on the system). -n Normalize hostnames. The name refereed to by ${rhost} is normalized relative to the host database before being used. The effect is to translate aliases into ``official'' names. -o op_sys_ver Override the compiled-in version number of the operating system. Useful when the built in version is not desired for backward compatibility reasons. For example, if the build in version is ``2.5.1'', you can override it to ``5.5.1'', and use older maps that were written with the latter in mind. -p Print PID. Outputs the process-id of amd to stan- dard output where it can be saved into a file. -r Restart existing mounts. Amd will scan the mount file table to determine which filesystems are cur- rently mounted. Whenever one of these would have been auto-mounted, amd inherits it. -t interval.interval Specify the interval, in tenths of a second, between NFS/RPC/UDP retries. The default is 0.8 seconds. The second values alters the restransmit counter. Useful defaults are supplied if either or both values are missing. -v Version. Displays version and configuration infor- mation on standard error. -w interval Specify an interval, in seconds, between attempts to dismount filesystems that have exceeded their cached times. The default is 2 minutes. 3 November 1989 2 AMD(8) AMD(8) -x options Specify run-time logging options. The options are a comma separated list chosen from: fatal, error, user, warn, info, map, stats, all. -y domain Specify an alternative NIS domain from which to fetch the NIS maps. The default is the system domain name. This option is ignored if NIS support is not available. -C cluster-name Specify an alternative HP-UX cluster name to use. -D option Select from a variety of debug options. Prefixing an option with the strings no reverses the effect of that option. Options are cumulative. The most useful option is all. Since -D is only used for debugging other options are not documented here: the current supported set of options is listed by the -v option and a fuller description is available in the program source. -F conf_file Specify an amd configuration file to use. See amd.conf(5) for description of this file's format. This configuration file is used to specify any options in lieu of typing many of them on the com- mand line. The amd.conf file includes directives for every command line option amd has, and many more that are only available via the configuration file facility. The configuration file specified by this option is processed after all other options had been processed, regardless of the actual loca- tion of this option on the command line. -H Print help and usage string. -O op_sys_name Override the compiled-in name of the operating sys- tem. Useful when the built in name is not desired for backward compatibility reasons. For example, if the build in name is ``sunos5'', you can over- ride it to ``sos5'', and use older maps which were written with the latter in mind. 3 November 1989 3 AMD(8) AMD(8) -S Do not lock the running executable pages of amd into memory. To improve amd's performance, systems that support the plock(3) call, could lock the amd process into memory. This way there is less chance the operating system will schedule, page out, and swap the amd process as needed. This tends improves amd's performance, at the cost of reserv- ing the memory used by the amd process (making it unavailable for other processes). If this behavior is not desired, use the -S option. -T tag Specify a tag to use with amd.conf(5). All map entries tagged with tag will be processed. Map entries that are not tagged are always processed. Map entries that are tagged with a tag other than tag will not be processed.
FILES
/a directory under which filesystems are dynamically mounted /etc/amd.conf default configuration file
CAVEATS
Some care may be required when creating a mount map. Symbolic links on an NFS filesystem can be incredibly inefficient. In most implementations of NFS, their inter- polations are not cached by the kernel and each time a symlink is encountered during a lookuppn translation it costs an RPC call to the NFS server. It would appear that a large improvement in real-time performance could be gained by adding a cache somewhere. Replacing symlinks with a suitable incarnation of the auto-mounter results in a large real-time speedup, but also causes a large number of process context switches. A weird imagination is most useful to gain full advantage of all the features.
SEE ALSO
amd.conf(5), amq(8), domainname(1), hostname(1), auto- mount(8), mount(8), umount(8), mtab(5), syslog(3). Amd - The 4.4 BSD Automounter
AUTHORS
Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Comput- ing, Imperial College, London, UK. Erez Zadok <ezk@cs.columbia.edu>, Department of Computer Science, Columbia University, New York, USA. 3 November 1989 4 AMD(8) AMD(8) Other authors and contributors to am-utils are listed in the AUTHORS file distributed with am-utils. 3 November 1989 5
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