#3140 Issue closed: How to mount USB device during recover (but not during mkbackup)?

Labels: support / question, fixed / solved / done

robertdahlem opened issue at 2024-01-26 18:29:

  • ReaR version ("/usr/sbin/rear -V"): Relax-and-Recover 2.6 / Git

  • If your ReaR version is not the current version, explain why you can't upgrade: First trying to run Ubuntu out of the box. Will happily try 2.7 or master when asked to.

  • OS version ("cat /etc/os-release" or "lsb_release -a" or "cat /etc/rear/os.conf"): Ubuntu 22.04

  • ReaR configuration files ("cat /etc/rear/site.conf" and/or "cat /etc/rear/local.conf"):

OUTPUT=USB
USB_DEVICE=/dev/disk/by-label/REAR-000
BACKUP=NETFS
BACKUP_URL=file:///media/myuser/EXT-PLATTE-1TB/rear
AUTOEXCLUDE_AUTOFS=y

  • Hardware vendor/product (PC or PowerNV BareMetal or ARM) or VM (KVM guest or PowerVM LPAR): KVM guest

  • System architecture (x86 compatible or PPC64/PPC64LE or what exact ARM device): x86_64

  • Storage (local disk or SSD) and/or SAN (FC or iSCSI or FCoE) and/or multipath (DM or NVMe): automounted USB device

  • Description of the issue (ideally so that others can reproduce it):

Ubuntu out of the box automounts any USB storage that gets attached under /media/myuser/$LABEL_OF_DEVICE_OR_PARTITION.

I can prevent that with LABEL=REAR-000 none none noauto 0 0 in /etc/fstab for the USB stick to create the ISO. But I do not wish to prevent this for the backup device because it holds other stuff too that shall stay visible to the (non-enlightened) user.

ReaR shall just use /media/myuser/EXT-PLATTE-1TB/rear during mkbackup but needs to mount /dev/disk/by-label/EXT-PLATTE-1TB to /media/myuser/EXT-PLATTE-1TB of whatever suitable path during recover.

Using BACKUP_MOUNTCMD fails at start of mkbackup with "already mounted".
Using BACKUP_URL=usb:///dev/disk/by-label/EXT-PLATTE-1TB also fails with "already mounted".

So my question is: how do I get ReaR to accept a mounted path as BACKUP_URL during mkbackup but to mount it by itself during mkrescue?

jsmeix commented at 2024-02-09 11:32:

Offhandedly (i.e. without any testing)
I would try to use bash scripting in etc/rear/local.conf
to make things behave different when you run ReaR
on the original system versus on the replacement system, cf.
https://github.com/rear/rear/blob/rear-2.7/etc/rear/local.conf

In the recovery system /etc/rear-release is unique
(it does not exist otherwise) so you can

test -f /etc/rear-release

to find out whether or not you are in the recovery system, cf.
https://github.com/rear/rear/blob/rear-2.7/usr/share/rear/lib/recover-workflow.sh#L23

What I do not know is how to make ReaR accept
an already mounted path as BACKUP_URL
without trying to mount it.
I fear you have to modify certain scripts.

robertdahlem commented at 2024-02-11 13:07:

@jsmeix I ended up with writing a wrapper script around "rear mkbackup" which does several checks (USB stuff actually attached) and does the necessary umount.

jsmeix commented at 2024-02-12 10:05:

@robertdahlem
thank you for your feedback how you solved it in your case
so others can see what a possible solution could be.

robertdahlem commented at 2024-02-12 13:28:

@jsmeix I added my wrappper script so it can be used as an example by others. Unfortunately, GitHub only accepts several extension, so one has to remove the ".txt" suffixes.
rear_wrapper.sh.txt
site.conf.txt

[Export of Github issue for rear/rear.]