I have a ZCM 10.3.4 service running on a XEN SLES11-sp1 paravrtualised DomU.
The ZCM upgrade to 11.2 instructions warn against extracting the ZCM 11.2 iso file and using that as the upgrade source, instead recommending creating a physical DVD and using that as the source.

As I have a vitualised server I assumed it would be easy to mount the iso as a virtual CD for the guest to use and crack on with the install... but after finding the virt-manager 'add a CD/DVD' option didn't
give me the results I was hoping for (a nice shiny CD icon on the desktop of the virtual server and a 'there it is!' moment after opening nautilus...) I attempted to follow the SuSE instructions for attaching
a CD reader Block device. This asks you to attach a device tap:cdrom:/dev/sr0 or file:/path to iso/ zcm112.iso to an unused block device (say xvdb) and then mount the block device to the DomU guest's
file system (/mnt/xvdb... for example).

This is great for accessing the data, but to my eyes accessing the DVD's installation files from a mounted directory on the guest server isn't any different to extracting the CD/DVD and trying to run the
install from the extracted files on a standard physical box.

Does anyone know why extracting the install iso isn't recommended and more importantly how to upgrade ZCM 10.3 running on a XEN virtual server to 11.2?