LDM Frequently Asked Questions

This page contains answers to some of the most frequently asked questions about the LDM.

Table of Contents

What is the LDM?

The LDM is a distributed system for event-driven data distribution. It consists of a suite of software to select, capture, process, and distribute data products using a set of network client/server programs and their shared protocols.

Who can use the LDM software?

The LDM software is being used by hundreds of universities and cooperating agencies and is freely available to anyone who wishes to use it. The software is copyrighted by the University Corporation for Atmospheric Research.

How do I get the LDM distribution?

The LDM software is freely available for download from the Unidata Program Center.

(IRIX 6.1) Why does my server deny RPC access to others?

In IRIX, version 6.1, there is a file, /etc/config/portmap.options. The -a option in this file disallows any host trying to do an RPC call to the machine. You must explicitly allow any hosts that will connect to you. See the man page for portmap for more information.

(IRIX) Why does my LDM die every Sunday at 4:30 am?

On IRIX systems, a disk defragger process runs every Sunday at 4:30 a.m. out of the root account. Because the product queue is a memory-mapped I/O file, it cannot be de-fragmented on disk while it is mapped. If it is, it corrupts the queue.

The solution is to either remove the root cron job that runs /usr/etc/fsr, or to add a -m switch pointing to a file that does not include the file system that contains the queue. This will allow other file systems to be de-fragmented, ignoring the data file system. See the man page for fsr for more information.

4/30/96: SGI now has a patch available that seems to fix the fsr problem: patchSG0000870 - EFS filesystem roll-up patch for non-XFS systems.

Why do I get the error that another server is running on port 388 when there is no other server active?

If the LDM server does not exit cleanly, port 388 may remain registered with the portmapper, even if the server is no longer running. Use rpcinfo to check this:

      % rpcinfo -p

If port 388 is still registered, as root, use rpcinfo to deregister the port:

      % rpcinfo -d 300029 version

where version is the version number of the program that is running, which will be 5 and/or 6.