Host names

LSF needs to match host names with the corresponding Internet host addresses.

LSF looks up host names and addresses the following ways:

  • In the /etc/hosts file

  • Sun Network Information Service/Yellow Pages (NIS or YP)

  • Internet Domain Name Service (DNS).

    DNS is also known as the Berkeley Internet Name Domain (BIND) or named, which is the name of the BIND daemon.

Each host is configured to use one or more of these mechanisms.

Network addresses

Each host has one or more network addresses; usually one for each network to which the host is directly connected. Each host can also have more than one name.

Official host name

The first name configured for each address is called the official name.

Host name aliases

Other names for the same host are called aliases.

LSF uses the configured host naming system on each host to look up the official host name for any alias or host address. This means that you can use aliases as input to LSF, but LSF always displays the official name.

Use host name ranges as aliases

The default host file syntax

ip_address official_name [alias [alias ...]]

is powerful and flexible, but it is difficult to configure in systems where a single host name has many aliases, and in multihomed host environments.

In these cases, the hosts file can become very large and unmanageable, and configuration is prone to error.

The syntax of the LSF hosts file supports host name ranges as aliases for an IP address. This simplifies the host name alias specification.

To use host name ranges as aliases, the host names must consist of a fixed node group name prefix and node indices, specified in a form like:

host_name[index_x-index_y, index_m, index_a-index_b]

For example: 

atlasD0[0-3,4,5-6, ...]

is equivalent to:

atlasD0[0-6, ...]

The node list does not need to be a continuous range (some nodes can be configured out). Node indices can be numbers or letters (both upper case and lower case).

Example

Some systems map internal compute nodes to single LSF host names. A host file might contains 64 lines, each specifying an LSF host name and 32 node names that correspond to each LSF host:

...
177.16.1.1 atlasD0 atlas0 atlas1 atlas2 atlas3 atlas4 ... atlas31
177.16.1.2 atlasD1 atlas32 atlas33 atlas34 atlas35 atlas36 ... atlas63
...

In the new format, you still map the nodes to the LSF hosts, so the number of lines remains the same, but the format is simplified because you only have to specify ranges for the nodes, not each node individually as an alias:

...
177.16.1.1 atlasD0 atlas[0-31]
177.16.1.2 atlasD1 atlas[32-63]
...

You can use either an IPv4 or an IPv6 format for the IP address (if you define the parameter LSF_ENABLE_SUPPORT_IPV6 in lsf.conf).

Host name services

Solaris

On Solaris systems, the /etc/nsswitch.conf file controls the name service.

Other UNIX platforms

On other UNIX platforms, the following rules apply:

  • If your host has an /etc/resolv.conf file, your host is using DNS for name lookups

  • If the command ypcat hosts prints out a list of host addresses and names, your system is looking up names in NIS

  • Otherwise, host names are looked up in the /etc/hosts file

For more information

The man pages for the gethostbyname function, the ypbind and named daemons, the resolver functions, and the hosts, svc.conf, nsswitch.conf, and resolv.conf files explain host name lookups in more detail.