Setting up slave servers

Your network can have one or more NIS slave servers. Having slave servers ensures the continuity of NIS services in the event of the master server being down. Before actually running ypinit(1Mnis) to create the slave servers, take several precautions.

First, as you did with the master NIS server, you must check that every slave server's password database contains an entry for the daemon user name and that it precedes other entries with the same user ID.

Also, make sure that the network is working properly before you set up a slave NIS server. In particular, check that you can use rcp(1tcp) to send files from the master NIS server to NIS slaves. If you cannot, follow the procedures outlined in ``Administering Remote Procedure Calls (RPC)'' to permit the use of rcp.

Now you are ready to create a new slave server. Perform the following procedure:

1. Log into each slave server as the NIS administrator.

2. If you want to modify the list of maps that a slave slaver will initially request from the master server, edit the list of maps in the file /var/yp/YPMAPS on the slave server before running ypinit. For example, you might want to include the names of the automounter maps, auto.master and auto.home, in this file.

3. Enter:
   
   /usr/sbin/ypinit -s master

   where master is the host name of the existing NIS master server.

   Ideally, the named host is the master server, but it can be any host with a stable set of NIS maps, such as another slave server.

   ypinit calls ypxfr(1Mnis) to transfer a copy of each map named in /var/yp/YPMAPS from the master server to the slave server's /var/yp/domainname directory.

4. It is usual to configure an NIS slave server as an NIS client as described in ``Setting up NIS clients''. This ensures that processes on the slave server also use the NIS services, rather than files in the local /etc directory.

   Make backup copies of the /etc/passwd and /etc/group files, and edit the original files by adding an entry such as ``+:'' to the end. This ensures that processes consulting those files will have access to the NIS maps. This applies also to whatever non-default maps you may have added to the Makefile. For instance, if there is an auto.direct NIS map, the file /etc/auto.direct should also be copied to another file and the original should contain a line similar to:

   +auto.direct
   

   Thus, whenever the automounter reads this file, it will consult the NIS auto.direct map upon reaching this line.