Dynamic Root Disk and MirrorDisk/UX

# /opt/drd/bin/drd mount
# /usr/bin/cp /var/opt/drd/registry/registry.xml \
/var/opt/drd/mnts/sysimage_00*/var/opt/drd/registry/registry.xml
# /opt/drd/bin/drd umount
The LVM infrastructure on the inactive image cannot be updated by LVM commands run on the
booted system; they will only change the LVM control information on the booted system itself. Instead,
the commands must be run when the system is booted.
A way to automate this process is to create an rc script that will rename /etc/lvmtab and re-create
it with vgscan –v when the inactive system image is booted, then remove itself. Here is a sample
creation of such a script:
# initfile=/sbin/init.d/lvm_update
# rcfile=/sbin/rc2.d/S900lvm_update
# /usr/bin/rm -rf $rcfile $initfile
# print "#!/sbin/sh " > $initfile
# print " /usr/bin/mv –f /etc/lvmtab /etc/lvmtab.old " >> $initfile
# print " /vgscan –v " >> $initfile
# print " rc = \$?" >> $initfile
# print " /usr/bin/rm -rf $initfile $rcfile " >> $initfile
# print " exit \$rc " >> $initfile
# /usr/bin/chmod 555 $initfile
# /usr/bin/chown bin:bin $initfile
# /usr/bin/ln -s $initfile $rcfile
Automating the Three Disk Scenario
It is desirable to minimize the amount of time a system disk is un-mirrored. On the other hand,
systems that are limited to three internal disks and policies that limit use of networked storage for boot
disks will need to keep the third disk for the mirror of the active system image. The steps above can
be performed by a startup (rc) script that is copied to the clone by the system administrator, runs at
boot of the clone, and then removes or renames itself. (Note that this startup script is distinct from the
one described in the section above. This script is created on the clone before booting. The script
described in the section above is created on the original system in case there is a need to boot back
to it.)
Two Disk Scenario – Splitting a Mirror to Provide a Clone
Disk
It is not recommended that an LVM mirror be broken off to provide a DRD clone, because this leaves
the operating system un-mirrored. Also, if a “broken mirror” disk is used for a DRD clone, the clone
must still be created by executing the usual drd clone command. However, if a system
administrator wants to pursue this approach (probably on a test system), the following steps can be
used:
1. Break off the mirror from the currently booted disk, by following the steps from the section
Splitting a Mirror from an Inactive Image to Provide a Free Disk (above). There is no need to
notify DRD about the broken mirror in this case, because it is not yet aware of the system
configuration.