Using one usb drive to keep 2 backups

[Scooty-Puff-Jr]

Newer to rear and trying to make a single 2T USB drive work as a backup spot for 2 devices. Already sorted out my site.conf for one device and formatted the drive once to work as the backup for it, but would like to do the same thing for my friends device, but they are not identical, close but personal preferences, aliases, etc are different so can't just use the one backup to restore without losing the personal touches.

Is it possible to take a usb drive, create 2 partitions, then format each partition to be a backup location for 2 separate devices using rear?

[jsmeix]

As far as I see it is (at least in practice) impossible
to use one USB disk to recover two different systems.

I think there is only one ReaR recovery system possible
for one USB disk because it is the data that is stored
inside the ReaR recovery system which is specific for the
original system where "rear mkrescue/mkbackup" was run
in particular the disklayout.conf file where information
about partitions, filesystems and mountpoints is stored.

I think with some (likely sophisticated) manual setup
it is even possible to use one USB disk to recover
two different systems (I never tried that myself)
but a precondition is that you use legacy BIOS
and SYSLINUX as USB bootloader.

I won't recommend to do that because too easily
something could go wrong and then you may end up
in a total disaster instead of a disaster recovery.

Using GRUB2 as USB bootloader currently supports only
recovery for one single system with one single backup,
see item (b) in #2666

Currently there is no guarantee at all that
I will find time to implement that item (b).

I prefer to keep things simple and straightforward
so one USB disk to recover only one particular system
with only one backup (lastest most up-to-date one)
is simpler and that results more fail-safe code
(better simple and straightforward code
than sophisticated and fragile constructs)
which in the end results more fail-safe recovery.

Even recovery for one single system with more than
one single backup (more than the lastest up-to-date one)
for that one system calls for trouble unless the user
took extra care to ensure all is fully consistent,
cf. #2787

This issue is not about several backups
but it shows that the ReaR recovery system
and the backup need to be fully consistent
i.e. even only one ReaR recovery system
with only one backup is already a problem
so more than one ReaR recovery system
plus more than one backup ensure trouble.

When you don't need all the space of a USB disk
for the ReaR recovery system and the backup
you can setup additional partitions and use them
as you like to store data but you must always
keep all intact what belongs to disaster recovery.

Of course using a USB disk that is meant for
disaster recovery also for other use cases
has the risk to accidentally damage something
on the disk that is needed for disaster recovery
so that disaster recovery would then no longer work.