LDM Platform Requirements

Contents

• General Requirements

• Requirements for Installing from Source-Code

General Requirements

Your computer must

• Run some variant of a UNIX^® operating system.

• Have a standard user-shell (e.g., sh(1), ksh(1), bash(1)) .

• Have sufficient local disk-space for the LDM product-queue, which can range from a few megabytes to many gigabytes in size -- depending on your data requirements.

• Have perl 5 installed.

• Have the uptime, vmstat, netstat, and top utilities installed if you wish to collect metrics on the performance of the LDM system via the ldmadmin addmetrics command.

• Have the gnuplot utility installed if you wish to plot metrics on the performance of the LDM system via the ldmadmin plotmetrics command, or the plotMetrics utility.

• Have an accurate and monotonic clock.

The last requirement is absolutely necessary because the LDM protocol depends on accurate clocks on both the upstream host and the downstream host.

Additionally, if the clock is not monotonic (because it is periodically set backwards by ntpdate(8), for example) then processes that read from the product-queue (such as upstream LDMs and pqacts will miss some data-products that are in the queue. This is because data-products reside in the product-queue in the order in which they were inserted into the queue according to the system clock. If the system clock jumps backwards, then a data-product might not be inserted at the tail of the queue and so be missed by a process waiting at the tail for the next product. The rate at which products will be missed depends, among other things, on the rate at which products are inserted into the queue, the frequency with which the system clock is adjusted backwards, and the amount of the adjustments.

Linux systems with kernels older than 2.6.18 (for 32-bit systems) or 2.6.21 (for 64-bit systems) are at high-risk for non-monotonic system clocks.

This requirement can be generally satisfied by running a Network Time Protocol daemon (ntpd). The NTP daemon is available at ntp.org. Information on public NTP time servers is available at http://ntp.isc.org/bin/view/Servers/WebHome. Linux users with the older kernels mentioned above should pay particular attention to the NTP support documentation on Known Hardware Issues and Known Operating System Issues.

Requirements for Installing from Source-Code

You must have a UNIX^® development-environment. In particular, your platform must have:

• A Standard C compiler.

• A standard rpcgen(1) utility.

• A standard make(1) utility.

• The lex(1) and yacc(1) utilities (or workalikes like byacc, bison, flex, etc.).

While every effort is made to ensure that the LDM source-code distribution can be compiled and installed on as wide a variety of UNIX^® platforms as possible, we can, necessarily, only test on platforms that are available at the Unidata Program Center (UPC).

With that in mind, the LDM package has been successfully built at the UPC on the following systems using the specified C compilers and make(1) utilities

Notes:

1. This is the output of the command "uname -s".

2. This is the output of the command "uname -r" unless otherwise noted.

3. This is the output of the command "uname -m".

4. This is the output of the command "echo $(uname -v).$(uname -r)" (AIX's interpretation of release and version differs from that of most other operating systems).

5. If this compiler is used, then the option --disable-max-size must be given to the configure script, which means that the resulting LDM will only support a small product-queue.

6. This is the output of the command "uname -p".

7. Alias SPARC.

The UPC reserves the right to deny support to outdated or irregular platforms.