Dynamic Root Disk aka DRD is root disk cloning tool from HP. This tools aims providing system integrity solution at maintenance activities performed on root disk. On DRD cloned disk you can perform any maintenance activity which you planned to do on actual live disk without worrying about disturbing running system. You can activate cloned disk and reboot server which then boots from altered cloned disk. If you observe your changes are not perfect, you can re-activate your old live root disk hence getting back to original state within minutes.
Proposed normal DRD clone disk life cycle is :
- Clone live root disk
- Mount cloned disk
- Make any changes you want on cloned disk
- Activate cloned disk and reboot server
- Now system boots from cloned disk (Your old live disk is intact!)
- If you want to go back to old state, set old live disk as primary boot disk
- Reboot system and your old live disk will be booted as it is.
Lets see different operations which can be done through dynamic root disk commands.
Learn how to configure Dynamic Root Disk (DRD) in HPUX. Understand how to clone root disk, view files in it, activate and deactivate DRD disk.
Dynamic Root Disk aka DRD is root disk cloning tool from HP. This tools aims providing system integrity solution at maintenance activities performed on root disk. On DRD cloned disk you can perform any maintenance activity which you planned to do on actual live disk without worrying about disturbing running system. You can activate cloned disk and reboot server which then boots from altered cloned disk. If you observe your changes are not perfect, you can re-activate your old live root disk hence getting back to original state within minutes!
Proposed normal DRD clone disk life cycle is :
- Clone live root disk
- Mount cloned disk
- Make any changes you want on cloned disk
- Activate cloned disk and reboot server
- Now system boots from cloned disk (Your old live disk is intact!)
- If you want to go back to old state, set old live disk as primary boot disk
- Reboot system and your old live disk will be booted as it is.
Lets see different operations which can be done through dynamic root disk commands.
1. How to clone root disk using DRD
DRD has its own set of commands to perform operations on clone disk. To clone your live root disk, attach / identify unused disk with same or more capacity than live root disk with same technology/model. Once identified, use below command :
DRD binary resides in /opt/drd/bin. Use clone argument to drd command and supply target disk path with -t option (which will be final cloned disk). There are few potion which can be used with -x. We used here to overwrite disk if any data resides in it. This command execution takes 30 mins to hours time depending on your root VG size.
At the end you can see system image has been cloned on disk /dev/dsk/c0t2d0 i.e. /dev/disk/disk6. You can check status of DRD using below command which lists all detaisl about cloned disk.
2. How to mount cloned disk
Once disk is cloned, you can view data within it by mounting it. Use mount argument with drd command.
This will create a new VG on your system named drd00 and mounts clone disk within it. All you rroot disk mount points in cloned disk will be mounted on /var/opt/drd/mnts/sysimage_000 e.g. /tmp in cloned disk will be available on /var/opt/drd/mnts/sysimage_000/tmp mount point. See below output for your understanding:
You can even un-mount DRD cloned disk using drd unmount command.
3. Different tasks which can be performed on cloned DRD disk
There are different maintenance activities which you can perform on this cloned DRD disk. To name few : patch installation, editing some system files manually, tuning static kernel parameters etc.
To execute tasks on cloned disk you need to supply commands as a argument to “drd runcmd” option. For example, if you want to view /etc/hosts file in cloned image, use “drd runcmd cat /etc/hosts”
See above example where I tune kernel parameters within cloned disk.
You can even install patches using this command (drd runcmd swinstall -s /tmp/patch123.depot). Even if patch which needs a reboot can be installed. Since you are installing it on cloned (non live) root disk, server wont be rebooted. To make these changes live on your server, you need to boot server with this cloned disk.
4. How to activate DRD cloned disk
To activate dynamic root disk, you need to run drd activate command. Actually this command sets your cloned disk path as a primary boot path which you can do by setboot command too!
If you set reboot to false, it will just set primary boot disk path and exists. After that when you manually reboot system, it will boot from cloned disk.
If you dont choose autoreboot then you will have chance to reverse activate operation using deactivatecommand argument.
5. After booting cloned disk
If you boot your system from dynamic root disk, below things will be changed :
- Root VG Mirroring will be missing
- Past live root disk will be intact
- Past live root disk will be removed from setboot primary/alternate boot path settings
- You have to restore root mirror
- You have to check and set alternate boot path
- You system will be having all changes (patch install, kernel tuning) you made on cloned disk
Dynamic Root Disk is very powerful tool when it comes to chopping down your downtime. If you have little downtime window and need to perform large number of patching which requires reboot. Patch cloned disk and just reboot server during your short downtime!
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