[SOLVED] bash script for internal disk backup: grub libata.force issue...

masavini · 03-11-2015, 07:00 PM

hi,
i have a desktop pc with 2 identical disks.

1 disk is used as "main" device. the other is used for internal backup purposes: every week i clone the main disk over the backup disk using dd.

in this way, if the main drive fails i can boot the pc using the backup drive and i'm done: i can take all my time to replace the faulty drive with no issue...

however, just after the cloning process the 2 disks are identical.
this leads to a big mess while mounting /etc/fstab devices, as the partitions of the 2 drives have the same UUIDs.

to fix this, i added the following line to /etc/default/grub of the main disk:

Code:

GRUB_CMDLINE_LINUX_DEFAULT="libata.force=2.00:disable"

and i added the following commands to the backup script:

Code:

# ... cloning stuff...

# mount backup root partition
sudo mount ${targetDisk}${rootPartitionN} mnt

# edit backup /etc/default/grub so that main disk is ignored
sudo sed -i 's/libata.force=2.00:disable/libata.force=1.00:disable/' mnt/etc/default/grub

# prepare chrooting into backup disk
for i in /dev /dev/pts /proc /sys /run; do
	sudo mount -B $i mnt$i
done

# update grub on backup disk
sudo chroot mnt update-grub
	
for i in /run /sys /proc /dev/pts /dev; do
	sudo umount mnt$i
done
sudo umount mnt

the script seems to be working fine, as the backup disk /etc/default/grub file is correctly edited.

- if both the drives are plugged in and i boot the system using the main drive, everything works fine: grub ignores the backup disk, as expected.

- if i unplug the main disk, i can boot the backup disk and everything works fine.

- but if both the drives are plugged in and i boot using the backup drive, it does not work: the screen is black, with a blinking cursor. after a few minutes the display powers off and i can only roughly power off the pc.

any suggestion?

fred2014 · 03-12-2015, 10:41 AM

what I do:
I have centos on 1 drive and windoze on another - both setup as bootable -
during boot - press F12 and select the drive I want. No more "grubbing" around...

Dont know if it will work for you though - give it a go.

masavini · 03-12-2015, 07:38 PM

fixed!

i found my syntax for the libata.force option was not correct.

from the kernel paramenters documentation:

Quote:

libata.force= [LIBATA] Force configurations. The format is comma

separated list of "[ID:]VAL" where ID is
PORT[.DEVICE]. PORT and DEVICE are decimal numbers
matching port, link or device. Basically, it matches
the ATA ID string printed on console by libata. If
the whole ID part is omitted, the last PORT and DEVICE
values are used. If ID hasn't been specified yet, the
configuration applies to all ports, links and devices.

in my configuration i was specifying both the PORT (n) and the DEVICE (.00). if i omit the DEVICE part, everything works fine..

so i changed the following line in /etc/default/grub of the main disk:

Code:

GRUB_CMDLINE_LINUX_DEFAULT="libata.force=2.00:disable"

to

Code:

GRUB_CMDLINE_LINUX_DEFAULT="libata.force=2:disable"

then i edited this line in the backup script:

Code:

sudo sed -i 's/libata.force=2.00:disable/libata.force=1.00:disable/' mnt/etc/default/grub

to this:

Code:

sudo sed -i 's/libata.force=2:disable/libata.force=1:disable/' mnt/etc/default/grub