HP XC System Software User's Guide Version 3.2

11 Advanced Topics
This chapter covers topics intended for the advanced user. This chapter addresses the following
topics:
• “Enabling Remote Execution with OpenSSH” (page 117)
• “Running an X Terminal Session from a Remote Node” (page 117)
• “Using the GNU Parallel Make Capability” (page 119)
• “Local Disks on Compute Nodes” (page 122)
• “I/O Performance Considerations” (page 123)
• “Communication Between Nodes” (page 123)
11.1 Enabling Remote Execution with OpenSSH
To reduce the risk of network attacks and increase the security of your HP XC system, the
traditional rsh, rlogin, and telnet tools are disabled by default, and OpenSSH is provided
instead. HP XC systems use the OpenSSH package to provide a more secure environment than
the traditional rsh, rlogin, and telnet tools. OpenSSH provides a secure, encrypted connection
between your system and the HP XC system.
However, OpenSSH requires, by default, that users enter their password every time that they
attempt to access a remote system. When first you use the ssh command to access the system,
or when attempting to use a tool such as TotalView to debug an application on the cluster, you
may be prompted to enter your password multiple times. To eliminate the multiple requests,
use the procedure described below. Alternatively, you can use the ssh_create_shared_keys
command, which is described in “Using the Secure Shell to Log In”
There are a number of ways in which to manage an OpenSSH environment. If you have not
already established your own procedures, the following procedure will help you to get started.
This procedure must be executed by each user, and assumes that your home directory is on a
file system that is shared across the cluster.
Log in to your account on the system and execute the following commands. Press the ENTER
key in response to all questions.
$ ssh-keygen -t dsa
$ cd ~/.ssh
$ cat id_dsa.pub >>authorized_keys
$ chmod go-rwx authorized_keys
11.2 Running an X Terminal Session from a Remote Node
This section illustrates running an X terminal session from a remote node. An X terminal session
can be invoked through SLURM or through LSF-HPC. Note that the procedure described in this
section creates an unencrypted X terminal session, which is considered unsecure. The information
in this section assumes the following:
• You are on a Linux, UNIX, or UNIX-like machine.
• You are on a non-HP XC machine, which is serving your local display.
• Your machine is on a trusted network.
Step 1. Determining IP Address of Your Local Machine
To begin, you need to determine the IP address of your monitor's display server (the machine
serving your monitor), as shown in the following steps. You will use this IP address in later
commands to run the X terminal session.
First, echo the display:
11.1 Enabling Remote Execution with OpenSSH 117