Maui Scheduler

14.5 Issues with Client Commands

Client Overview:

Maui clients are implemented as symbolic links to the executable maui_client. When a maui client command is run, the client executable determines the name under which it is run and behaves accordingly. At the time Maui was configured, a home directory was specified. The Maui client will attempt to open the config file maui.cfg in this home directory on the node where the client command is executed. This means that the home directory specified at configure time must be available on all hosts where the maui client commands will be executed. This also means that a maui.cfg file must be available in this directory. When the clients open this file, they will try to load the MAUISERVER and MAUIPORT parameters to determine how to contact the Maui server.
Note The home directory value specified at configure time can be overridden by creating an /etc/maui.cfg file or by setting the 'MAUIHOMEDIR' environment variable.

Once the client has determined where the Maui server is located, it creates a message, adds an encrypted checksum, and sends the message to the server. Note that the Maui client and Maui server must use the same secret checksum seed for this to work. When the Maui server receives the client request and verifies the checksum, it processes the command and returns a reply.

Diagnosing Client Problems:

The easiest way to determine where client failures are occurring is to utilize built in maui logging. On the client side, use the '-L' flag. For example,

showq -L9

NOTE: Maui 3.0.6 and earlier specified the desired client side logging level using the '-D' flag (i.e., showq -D 9)

This will dump out a plethora of information about loading the configfile, connecting to the maui server, sending a request, and receiving a response. Wading through this information almost always will reveal the source of the problem. If it does not, the next step is to look at the maui server side logs. The easiest way to do this is to use the following steps:

schedctl -s
(stop Maui scheduling so that the only activity is handling maui client requests)
changeparam LOGLEVEL 7
(set the logging level to 'very verbose')
tail -f log/maui.log | more
(tail the maui.log activity)

(In another window)


The maui.log file should record the client request and any reasons it was rejected.