System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP)

Servers Have Different Versions of an NIS Map

Because NIS propagates maps among servers, occasionally you might find different versions of the same map on various NIS servers on the network. This version discrepancy is normal add acceptable if the differences do not last for more than a short time.

The most common cause of map discrepancy is that something is preventing normal map propagation. For example, an NIS server or router between NIS servers is down. When all NIS servers and the routers between them are running, ypxfr should succeed.

If the servers and routers are functioning properly, check the following:

Logging ypxfr Output

If a particular slave server has problems updating maps, log in to that server and run ypxfr interactively. If ypxfr fails, it tells you why it failed, and you can fix the problem. If ypxfr succeeds, but you suspect it has occasionally failed, create a log file to enable logging of messages. To create a log file, enter the following on the slave.

ypslave# cd /var/yp
ypslave# touch ypxfr.log

This creates a ypxfr.log file that saves all output from ypxfr.

The output resembles the output ypxfr displays when run interactively, but each line in the log file is time stamped. (You might see unusual ordering in the time-stamps. That is okay – the time-stamp tells you when ypxfr started to run. If copies of ypxfr ran simultaneously but their work took differing amounts of time, they might actually write their summary status line to the log files in an order different from that which they were invoked.) Any pattern of intermittent failure shows up in the log.

Note –

When you have fixed the problem, turn off logging by removing the log file. If you forget to remove it, it continues to grow without limit.

Check the crontab File and ypxfr Shell Script

Inspect the root crontab file, and check the ypxfr shell script it invokes. Typographical errors in these files can cause propagation problems. Failures to refer to a shell script within the /var/spool/cron/crontabs/root file, or failures to refer to a map within any shell script can also cause errors.

Check the ypservers Map

Also, make sure that the NIS slave server is listed in the ypservers map on the master server for the domain. If it is not, the slave server still operates perfectly as a server, but yppush does not propagate map changes to the slave server.

Work Around

If the NIS slave server problem is not obvious, you can work around it while you debug using rcp or ftp to copy a recent version of the inconsistent map from any healthy NIS server. The following shows how to transfer the problem map.

ypslave# rcp ypmaster:/var/yp/mydomain/map.\* /var/yp/mydomain

The * character has been escaped in the command line, so that it will be expanded on ypmaster, instead of locally on ypslave.