This document describes the Dynamic Root Disk (DRD) toolset, which
you can use to perform software maintenance and recovery on an HP-UX
operating system with minimum system downtime. Using DRD, you can
easily and safely clone a system image from a root disk to another
disk on the same system.
Using DRD commands, you can apply patches or make other modifications
to the cloned system image without affecting the active system image.
When ready, you can reboot the system and switch from the active system
image to the cloned system image. The only downtime required for this
process is while the system reboots.
Hewlett-Packard developed DRD to minimize the usual maintenance
window during which you shut down the system to install patches. With
DRD, the system keeps running while you clone the system image and
apply patches to the cloned image. DRD tools can manage the two system
images simultaneously. DRD also provides a fail safe mechanism for
returning the system to its original state, if necessary.
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