Networking

Linux Virtual Server for HP XC System Alias

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 cluster 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 cluster is configured in order to successfully log in and use the cluster. 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. Figure 1-1 illustrates the use of LVS in an HP XC system.

Figure 1-1 LVS View of Cluster

Network Time Protocol

One node in an HP XC system acts as the internal Network Time Protocol (NTP) server for all the other nodes. By default this is the head node. All other nodes are NTP clients of this server.

You can specify where the internal NTP server gets the time. You can specify up to three external time sources if the internal server has a connection to an outside network. You can also choose to use the internal server's own clock as the time source.

Should something go wrong and you notice a problem with the clocks synchronizing on any nodes, verify the internal server's /etc/ntp.conf file and the ntp.conf file on the nodes that are experiencing the problem.

Other tools, such as ntpq and ntpdc, are also available. For more information, see ntpd(1), ntpq(1), and ntpdc(1) and the ntp.conf file.

Network Address Translation

The HP XC system uses Network Address Translation (NAT) to enable nodes in the HP XC system without direct external network connections to open outbound network connections to external addresses. NAT enables application nodes to access network-available resources without the additional network management, resources, or load of making application nodes part of an external public network.

Network Information Service

The configuration of Network Information Service (NIS) on an HP XC system is an optional step that is useful for easing user management and helpful for SLURM and LSF-HPC use. You may decide to set up your user management with some other software, such as Lightweight Directory Access Protocol (LDAP).

Use either of the following methods for setting up NIS on your HP XC system: