Administering Platform LSF - SAS

Chapter 4
Working with Hosts
Hosts with Multiple Addresses
Multi-homed
hosts
Multiple network interfaces
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
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
Example
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.
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
Administering Platform LSF 89