The HP XC system relies on networking services
to communicate among its nodes. It uses the Linux Virtual Server,
Network Time Protocol, Network Address Translation, and Network Information
Service.
Linux Virtual Server for HP XC Cluster Alias |
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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 it. 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 1-3 illustrates the use of LVS in an HP XC system.
Network Time Protocol |
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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 four 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.
If something goes 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 |
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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 |
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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 with SLURM 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:
Set all the nodes as NIS clients. Both the master and slave NIS server are external to the HP XC system.
Set the head node as a NIS slave (secondary) server.
The NIS master server is external to the HP XC system. Nodes
within the HP XC system use the internal server for NIS information. HP recommends
this configuration for larger systems using NIS.
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