DRD-Safe Concepts for HP-UX 11i v2 and Later

An additional step is needed to address the following scenario: A system administrator may use DRD
to remove a product or fileset from the inactive system image and then use DRD to install (the same or
a different version of) the product or fileset to the inactive system image. Both operations may be
done without an intervening reboot.
In the case described above, an install control script must remove the rc script and the S900
symlink that were deployed by the remove script. The Ignite product uses a product preinstall
script for this purpose, but a BOOT-SERVICES control script could easily have been used. Note that
this code need not be conditional on running in a DRD session. The file system changes will be on the
inactive system image if the install is running in a DRD session. However, there is no harm in
removing them from the booted system in the unlikely event that they are found in a non-DRD
installation.
The code used by the Ignite preinstall script is shown below.
#
# Clean up DRD-safety files that may have been left by unconfigure
# when a swremove of Ignite was done to a DRD clone, then swinstall
# Ignite was performed before the DRD was rebooted. These files
# are defined in the BOOT-SERVICES unconfigure script.
#
initfile=/sbin/init.d/iux_unconf
rcfile=/sbin/rc2.d/S900iux_unconf
rm -rf $rcfile $initfile
4.3 Logic to Support NFS Diskless may not be DRD-safe
While logic to support NFS diskless is obsolete and should be removed from the control script, the
presence of such logic (that is, check for SW_DEFFERRED_KERNBLD) is a good indication of logic
that may not be DRD-safe and should be examined closely to determine if it is safe or not.