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Networking stack and configuration

Overview

This document describes the network stack initialization and slcfg(5) automatic profile self discovery.

The following actions are taken depending on the value of the nets slcfg(5) option:

• if nets is a single Lustre network name (e.g. tcp10), tuples of (network interface, Lustre network name) pairs are constructed from each interface address registered in the system and this specified Lustre network name. The resulting list of pairs is copied into the daemon process LNET_NETWORKS environment variable.

• if nets is a fully fledged LNET_IP2NETS value, this value is used verbatim to determine which addresses held by SLASH2 peers correspond to which Lustre networks and the system's network interfaces are queried to determine links to use to reach such peers.

These behaviors will be overridden if LNET_NETWORKS is already specified in the process environment during daemon launch, which always takes precedence.

Otherwise, LNET_NETWORKS is constructed from the values specified for the nids attribute of all nodes in the SLASH2 configuration file slcfg.

LNET_NETWORKS is then parsed to determine routable addresses and their corresponding Lustre network names. These pairs are used to assign Lustre networks to the resource node addresses listed in the slcfg(5) site resources configuration.