Platform LSF Administration Guide Version 6.2

Chapter 4
Working with Hosts
Administering Platform LSF
115
Hosts with Multiple Addresses
Multi-homed
hosts
Hosts that have more than one network interface usually have one Internet address for
each interface. Such hosts are called multi-homed hosts. LSF identifies hosts by name, so it
needs to match each of these addresses with a single host name. To do this, the host
name information must be configured so that all of the Internet addresses for a host
resolve to the same name.
There are two ways to do it:
◆ Modify the system hosts file (/etc/hosts) and the changes will affect the whole
system
◆ Create an LSF hosts file (LSF_CONFDIR/hosts) and LSF will be the only
application that resolves the addresses to the same host
Multiple network interfaces
Some system manufacturers recommend that each network interface, and therefore,
each Internet address, be assigned a different host name. Each interface can then be
directly accessed by name. This setup is often used to make sure NFS requests go to the
nearest network interface on the file server, rather than going through a router to some
other interface. Configuring this way can confuse LSF, because there is no way to
determine that the two different names (or addresses) mean the same host. LSF provides
a workaround for this problem.
All host naming systems can be configured so that host address lookups always return
the same name, while still allowing access to network interfaces by different names. Each
host has an official name and a number of aliases, which are other names for the same
host. By configuring all interfaces with the same official name but different aliases, you
can refer to each interface by a different alias name while still providing a single official
name for the host.
Configuring the LSF hosts file
If your LSF clusters include hosts that have more than one interface and are configured
with more than one official host name, you must either modify the host name
configuration, or create a private
hosts file for LSF to use.
The LSF
hosts file is stored in LSF_CONFDIR. The format of
LSF_CONFDIR/hosts is the same as for /etc/hosts.
In the LSF
hosts file, duplicate the system hosts database information, except make
all entries for the host use the same official name. Configure all the other names for the
host as aliases so that people can still refer to the host by any name.
Example
For example, if your /etc/hosts file contains:
AA.AA.AA.AA host-AA host # first interface
BB.BB.BB.BB host-BB # second interface
then the LSF_CONFDIR/hosts file should contain:
AA.AA.AA.AA host host-AA # first interface
BB.BB.BB.BB host host-BB # second interface