#3398 Issue open: Creating a Config and when or IF a Disk gets formatted¶
Labels: support / question
AnnieSixgun opened issue at 2025-02-08 09:34:¶
Requesting support or just a question¶
question
Platform¶
Linux x64
Output¶
Additional information¶
I am new to rear ,
I would like to backup my entire linux mint system to a 12TB external
drive so I can reinstall the system or install the system on a new
computer, and just log in and go.
The 12TB external drive has a lot of data already on it that I want to
keep.
I read comments on some sites that my external drive will be formatted
and I will lose my data,
while other sites say I can choose to write an ISO to a Directory on my
external disk without my losing existing data.
I thought a config containing the below would work, but am afraid to try it unless someone at rear can assure me the program will not delete my existing files..or format my disk .... etc..
I created the config below from my understanding of the information I have read.. should it work ??
Do I need to add anything else to it ??
OUTPUT=ISO
OUTPUT_URL=file:///mnt/12TB_ext/rear/output/
BACKUP=NETFS
BACKUP_URL=file:///mnt/12TB_ext/rear/iso/
Thank you,
Anne
jsmeix commented at 2025-02-10 13:28:¶
ReaR is a disaster recovery tool that
complements backup and restore of files
but ReaR is neither a backup software
nor a backup management software
and it is not meant to be one.
ReaR is a system administrator tool and framework
to create a bootable disaster recovery system image
for bare metal disaster recovery with data backup
restore on physical or virtual replacement hardware.
For bare metal disaster recovery the ReaR recovery system
is booted on pristine replacement hardware.
On replacement hardware first the storage setup/layout is
recreated (disk partitioning, filesystems, mount points),
then a backup restore program is called to restore the
data (system files) into the recreated storage, and
finally a boot loader is installed.
To use ReaR from an external disk, the ReaR recovery system
must be bootable from that disk which means that disk must
be prepared to be UEFI or BIOS bootable which means
appropriate partitions for booting must be set up
which means one has to format that disk appropriately.
In theory it could be possible to prepare an already used disk
so that it is usable for ReaR but I think in practice this
needs unreasonable trial-and-error efforts compared to using
"rear format" from scratch with a pristine empty disk.
See our "QUICK START GUIDE" at
https://github.com/rear/rear
and also on
https://relax-and-recover.org/documentation/getting-started
for an initial simple way how to do that with OUTPUT=USB.
I recommend to use "rear mkbackup" only with a dedicated
disk for ReaR. This is what basically all others do so this
is proven to work reasonably well "out there in the wild".
If you use a disk where already valuable other data is stored
(e.g. a disk where already a previous backup is stored)
something might go terribly wrong when writing a subsequent
backup there (e.g. via "rear mkbackup") so in the end
all might be lost on that disk.
To be reasonably on the safe side you should use at least
two separated disks for ReaR and use them alternating.
With OUTPUT=ISO you would get a UEFI or BIOS bootable
ISO image but then you somehow need to dump ("burn") that
on a disk-like thingy (usually a real or virtual CD/DVD medium)
to actually boot from the ISO which means the whole medium
gets overwritten from its very beginning with the ISO image
so also in this case all existing data on that medium
will usually be lost.
Regarding re-installing the system on a new computer:
Fully compatible replacement hardware is needed for that.
When the new computer is not fully compatible it is not
a re-installation but a migration onto different hardware.
See the section
"Fully compatible replacement hardware is needed" in
https://en.opensuse.org/SDB:Disaster_Recovery
In general migrating a system onto different hardware
(where "hardware" could be also a virtual machine)
does not "just work", cf. "Inappropriate expectations" at
https://en.opensuse.org/SDB:Disaster_Recovery
In sufficiently simple cases it may "just work" but in general
do not expect too much built-in intelligence from a program
(written in plain bash which is not a programming language
that is primarily meant for artificial intelligence ;-)
to automatically do the annoying legwork for you.
In general ReaR is first and foremost meant to recreate
a system as much as possible exactly as it was before.
Additionally ReaR supports to migrate a system
but here "supports" means that ReaR provides a lot
that should help you to get such a task done
but it does not mean that it would "just work" without
possibly laborious manual settings and adaptions
with trial and error legwork until you made things work
for you in your particular case.
FYI:
For examples of more advanced things you may have a look at
https://github.com/rear/rear/issues/2553#issuecomment-784276218
https://github.com/rear/rear/issues/2553#issuecomment-785069808
https://github.com/rear/rear/issues/2530#issuecomment-734731740
gdha commented at 2025-02-24 12:38:¶
@AnnieSixgun Has your query been answered?
[Export of Github issue for rear/rear.]