HP XC System 2.x Software - Manual (Page 22)

nodes of the system. The system interconnect network is a private network within the HP XC.
Typically, every node in the HP XC is connected to the system interconnect.
The HP XC system interconnect can be based on either Gigabit Ethernet or Myrinet-2000
switches. The types of system interconnects that are used on HP XC systems are:
• Myricom Myrinet on HP Cluster Platform 4000 (ProLiant/Opteron servers), also referred to
as XC4000 in this manual.
• Quadrics QsNet II on HP Cluster Platform 6000 (Integrity servers), also referred to as
XC6000 in this manual.
• Gigabit Ethernet on both XC4000 and XC6000
• InfiniBand on XC4000
1.1.6 Network Address Translation (NAT)
The HP XC system uses Network Address Translation (NAT) to allow nodes in the HP XC
system that do not have direct external network connections to open outbound network
connections to external network resources.
1.2 User Environment
This section introduces some basic general information about logging in, configuring, and using
the HP XC environment.
1.2.1 LVS
The HP XC system uses the Linux Virtual Server (LVS) to present a single host name for user
logins. LVS is a highly scalable virtual server built on a system of real servers. By using LVS,
the architecture of the HP XC system is transparent to end users, and they see only a single
virtual server. This eliminates the need for users to know how the system is configured in
order to successfully log in and use the system. Any changes in the system configuration are
transparent to end users. LVS also provides load balancing across login nodes, which distributes
login requests to different servers.
1.2.2 Modules
The HP XC system provides the Modules Package (not to be confused with Linux kernel
modules) to configure and modify the user environment. The Modules Package enables
dynamic modification of a user’s environment by means of modulefiles. Modulefiles provide
a convenient means for users to tailor their working environment as necessary. One of the
key features of modules is to allow multiple versions of the same software to be used in
a controlled manner.
A modulefile contains information to configure the shell for an application. Typically, a
modulefile contains instructions that alters or sets shell environment variables, such as
PATH
and MANPATH , to enable access to various installed software. Modulefiles may be shared by
many users on a system, and users may have their own collection to supplement or replace the
shared modulefiles.
Modulefiles can be loaded into the your environment automatically when you log in to the
system, or any time you need to alter the environment. The HP XC system does not preload
modulefiles.
1.2.3 Commands
The HP XC user environment includes standard Linux commands, LSF commands, SLURM
commands, HP-MPI commands, and modules commands. This section provides a brief
overview of these command sets.
1-4 Overview of the User Environment