IBM SG24-5131-00 manual Cron and NIS Considerations

3.1.4.3Editing the /etc/hosts File and Nameserver Configuration Make sure all nodes can resolve all cluster addresses. See the chapter on planning TCP/IP networks (the section Using HACMP with NIS and DNS) in the HACMP for AIX, Version 4.3: Planning Guide, SC23-4277for more information on name serving and HACMP.

Edit the /etc/hosts file (and the /etc/resolv.conf file, if using the nameserver configuration) on each node in the cluster to make sure the IP addresses of all clustered interfaces are listed.

For each boot address, make an entry similar to the following:

100.100.50.200 crab_boot

Also, make sure that the /etc/hosts file on each node has the following entry:

127.0.0.1loopback localhost

3.1.4.4 cron and NIS Considerations

If your HACMP cluster nodes use NIS services, which include the mapping of the /etc/passwd file, and IPAT is enabled, users that are known only in the NIS-managed version of the /etc/passwd file will not be able to create crontabs. This is because cron is started with the /etc/inittab file with run level 2 (for example, when the system is booted), but ypbind is started in the course of starting HACMP with the rcnfs entry in /etc/inittab. When IPAT is enabled in HACMP, the run level of the rcnfs entry is changed to -aand run with the telinit -acommand by HACMP.

In order to let those NIS-managed users create crontabs, you can do one of the following:

•Change the run level of the cron entry in /etc/inittab to -aand make sure it is positioned after the rcnfs entry in /etc/inittab. This solution is recommended if it is acceptable to start cron after HACMP has started.

•Add an entry to the /etc/inittab file like the following script with run level -a. Make sure it is positioned after the rcnfs entry in /etc/inittab. The important thing is to kill the cron process, which will respawn and know about all of the NIS-managed users. Whether or not you log the fact that cron has been refreshed is optional.

58 IBM Certification Study Guide AIX HACMP