Tiered (or cascading) differencing disks

[GregHeeley]

Can the below scenario be achieved.
Normally I use Virtual PC. What I have done in the past is build a Single OS disk, then created a differencing disk on top to install relevant apps, then built another differencing disk on top to do particular tasks. So an example layout would look like this.

Base disk (Win XP, Printers, IIS,)
|
|
_________________________ |________________________
| |
| |
Develop Disk (VS 2008)(diff on base) Develop Disk (VS2010)(diff on Base)
| |
_______________|________________ ________________|________________
| | | |
| | | |
Apps Disk (office XP) Apps Disk(Office 2007) Apps Disk(Office 2007) Apps Disk(Office 2010)

With VBox, I can get as far as the develop disk (so build base, set to immutable, build develop using base as existing disk to get differencing image, then set autoreset set to off). But this disk cannot be set to immutable (Vbox manage reports differencing disks cant be immutable). Any advice on how to achieve this with Virtual Box? Really good article on VPC usage of above here http://www.andrewconnell.com/blog/artic ... ntage.aspx

[MarkCranness]

But this disk cannot be set to immutable (Vbox manage reports differencing disks cant be immutable). Any advice on how to achieve this with Virtual Box?

Yes. Create a 'holding' VM and attach the 'Develop Disk (VS 2008)(diff on base)' differencing disk to it, then take a snapshot.
Then when you attach that same diff disk to the 'Apps Disk (office XP)' VM, VirtualBox will attach it AS IF it was immutable (via a blue star) and create a new differencing disk for it.
(Once you have created the bottom level VMs, you can release (using Virtual Media Manager) the the 'holding' VM's snapshot and delete the VM.)
Repeat for the 'Develop Disk (VS2010)(diff on Base)' branch of the tree.

(You can in fact use this 'holding' VM idea from the start, rather than setting the original base disk to immutable.)