wiki:Larvnet

Version 2 (modified by jdreed, 10 years ago) (diff)

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Larvnet is the cluster monitoring system which gathers the data returned by the "cview" command--a list of free machines of each type in the Athena clusters, and a list of the number of current jobs pending on Athena printers.

When a user logs in or out of an Athena machine, or when an Athena machine starts up the login system, the machine sends a status packet to the Larvnet server. The status packet gives the machine's name, host type, and an determination of whether any user is logged into the machine at the console. Workstations can also be queried for the same status information using the "busyd" UDP service, which runs out of inetd. The Larvnet server separates machine names into clusters according to a configuration file and produces a data file once per minute containing counts of the free machines in each cluster of each type.

The Larvnet server also queries the print spooler for each Athena printer once per minute, using an "lpq" query. (Sadly, the output returned by "lpq" is not standardized well enough to be robustly machine-readable, so the mechanism here sometimes requires maintenance when changes are made to the printing system.)