Hi,
Is there a preferred way to install Debian 7
from DVD to an external (USB) hard disk ?
Euh... just install it on that disk? ;-)
The whole external hard disk is to be used instead of the internal hard disk.
Ok, no problem.
This is to experiment with the new release (and discover fish hooks like
graphics that don't work) while leaving the internal hard disk with the
production Debian 6 on it completely alone.
Sensible.
One then boots from either the external hard disk or the internal hard disk.
Yes and no, but read on.
To set this up, at what stage in the install process does one actually put the new release on to the external disk ?
When it asks which disk to set it up to and whether you want to do the partitioning yourself (manual) or guided.
Does one need to also tell the install program where to put grub ?
or does it do that automatically ?
You just stated above you have a production version of Debian on the internal disk, so it has Grub already. The new installation on the external disk just needs to be added to the existing Grub config. The installer should do that for you.
Is there any other special configuration one needs to do to properly
put the new release on to the external hard disk ?
Not that I know of.
It is vastly preferable not to unplug the internal hard disk or otherwise disrupt the functioning system.
No, the installer needs to access the Grub config on that disk. Unplugging it would also change the name of the disks (sda, sdb, etc) and might interfere with the installation or later on with running it, although it should not when using the default disk labels.
Of course the internal hard disk will be backed up before the attempted install ...
Yes, please do so. ;-)
Bonno Bloksma