/etc/beowulf/conf.d/nsswitch.conf -- NSS config file for compute nodes
Name Service Switch (NSS) is configured by the
which describes what sources the
Name Service uses to resolve queries
for each database category.
For example, simple
nsswitch.conf entries are:
passwd: files group: files hosts: files dns
A query for a user password uses the passwd database,
which informs the
Name Service to search the file
A query for a group name uses the group database,
A query for a host name uses the hosts database,
/etc/hosts, and then if that fails to find the name,
/lib64/libnss_dns.so to query the DNS server.
The Scyld ClusterWare beonss package enhances the
Name Service to
provide consistent naming across the cluster.
Installing the beonss package modifies the master's
adding "beo" and "bproc" sources to various database categories.
For example, for the hosts database, the "beo" source uses functionality in
/lib64/libnss_beo.so, interpreting the
nodename and iprange values to translate the node name "n32" into that
node's IP address,
and the "bproc" source uses
/lib64/libnss_bproc.so to translate
the node name ".32" into the same IP address result.
/etc/beowulf/conf.d/nsswitch.conf is copied to each booting compute node
and installed there as
A file with a numeric suffix, e.g.,
/etc/beowulf/conf.d/nsswitch.conf.32, specifies an alternative
node-specific file, in this case copied to node n32 at boot time.
/etc/nsswitch.conf on compute nodes understands the same "bproc"
source, plus an additional "kickback" source for various
categories, using functionality in
to further query the master node for name resolution,
assuming that the
/etc/beowulf/init.d/03kickbackproxyd is enabled on
the master node.
For example, suppose the compute node's
passwd: files kickback group: files kickback hosts: files bproc kickback
The addition of a new user and group on the master node amends the master's
although that does not affect those files on the already-booted compute nodes.
When a compute node client subsequently asks for that new user name's
password, the compute node's
Name Service fails when searching the
passwd "files" source,
then the "kickback" functionality queries the master node for the name,
which successfully replies with the new user's password information.