Dynamic Root Disk(DRD) in HP-UX

Author : Bibith Dathan
what is DRD ?

Dynamic Root Disk (DRD) is an HP-UX system administration toolset used to clone an HP-UX system image to an inactive disk for software maintenance and recovery.   DRD is available for download from the hp software depot for free (software.hp.com).
In case of system crash/OS software corruption, the system can be booted from the DRD disk(i.e alternate boot disk). Thus faster system recovery is achieved using this approach(<1hr in ideal conditions).
DRD toolset additionally offers solutions such as adding of softwares/patches to the cloned disk online, once the patches/softwares are installed to the cloned disk, the system can be booted from the cloned disk. Thereby reducing the system downtime while installing and updating patches and other software.
DRD is supported on the following platforms:
  • Systems—including hard partitions (nPars), virtual partitions (vPars), and Integrity Virtual Machines (VMs)—running either HP-UX 11i Version 2 (September 2004 or later) or HP-UX 11i Version 3
File systems: LVM and VxVM root volume

Additional product information

Product #:
Software specification:
HP-UX 11i v2 (11.23) DRD 0803
HP-UX 11i v3 (11.31) DRD 0803

1) Ensure the product DynRootDisk is installed.
swlist –i product|grep –i Dyn

2) Create clone disk:
a. Perform clone preview(-p) to check the disk size & suitability
/opt/drd/bin/drd clone –p –v –t /dev/dsk/cxtxdx
b. To clone OS onto target disk /dev/dsk/c3t3d0:
/opt/drd/bin/drd clone -x overwrite=true -v -t /dev/dsk/c3t3d0

The target disk is put under the vg drdnn and the drdnn vg is exported.
‘drd mount’ is run to activate the drdnn vg
‘drd clone’ command log is /var/opt/drd/drd.log

3) ‘drd activate’ sets the drd disk to be primary boot device. Now when the system reboots, it boots from the drd(alternate boot disk).
# /opt/drd/bin/drd activate

# /opt/drd/bin/drd activate –x reboot=true          
[This command sets the drd disk as primary boot disk & as well immediately reboots the machine]

4) ‘drd mount’
To perform any software maintenance/installation operations, the drd disk should have to be mounted first, which means that the drd disk/vg gets activated & drd /(root) filesystem get mounted under /var/opt/drd/mnts/sysimage_001/ mountpoint. Thereafter we can manually mount other OS filesystems of drd disk/vg under /var/opt/drd/mnts/sysimage_001/ mountpoint.

For ex: to mount /opt filesystem of drd disk/vg, we perform:
# /opt/drd/bin/drd mount
# /usr/sbin/mount /dev/drd00/lvol6 /var/opt/drd/mnts/sysimage_001/opt

Once the maintenance operations are complete, you can perform umount of the drd disk/vg, which shall umount filesystems & export the drd vg:
# /opt/drd/bin/drd umount.

5) To add patches/pkgs to the drd disk, you can use the “drd runcmd command
Here is a sample command used to apply QPKAPPS and QPKBASE to the DRD disk.
# /opt/drd/bin/drd runcmd swinstall \ -s depot_svr:/var/depots/1123_0706 QPKBASE QPKAPPS

In particular, the drd clone operation does the following:
• Creates Extensible Firmware Interface (EFI) partitions on HP-UX Integrity systems
• Creates boot records
• Creates a new LVM volume group or VxVM disk group and a volume in the new group for each volume in the root volume group. The volume management type of the clone matches that of the root group.
• Configures swap and dump volumes
• Copies the contents of each file system in the root volume group to the corresponding file system in the new group
• Modifies particular files on the clone that identify the disk on which the volume group resides
• For LVM-based systems, modifies volume group metadata on the clone so that the volume group name is the same as the original root volume group when the clone is booted

Other notes:
• The clone that has been created is not visible (when executing commands such as bdf or vgdisplay) at the completion of the clone operation. This is because the file systems on the clone are unmounted and the clone volume group is exported at completion of the drd clone command.

• The clone volume group and component logical volumes can be made visible by a drd mount command, which vgimports the clone volume group and mounts the file systems on the logical volumes. If the root group is named “vg00”, the imported clone group is “drd00”. More generally, if the root group is name “vgnn”, the clone group is “drdnn”. If the root group does not have the form “vgnn”, the clone group name is formed by prefixing the root group with “drd”.

• When the clone is booted, the root group is the same as the original root group that was cloned. 

Author : Dathan

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