Admin at 03:44, 20 January 2016

2016-01-20T03:44:35Z

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This is a command to copy the current (running, live) root filesystem to another (attached) disk. Last tested with Debian 8.1 (Jessie) and all works fine.

* add the new disk (e.g. /dev/sdb) to the system
* set up a linux partition and make it active (enable boot flag)
* format the target filesystem to ext2
* mount the target filesystem to /mnt

* copy files across..
<pre>
(cd / ; tar -cf - . --one-file-system) | (cd /mnt ; tar xvfpB - )
cp -r /dev/* /mnt/dev/
</pre>

* find out new disk UUID (ls /dev/disk/by-uuid/....)

* update UUID's in fstab and grub.cfg
<pre>
sed -i 's/old-uuid/new-uuid/g' /mnt/etc/fstab
sed -i 's/old-uuid/new-uuid/g' /mnt/boot/grub/grub.cfg
</pre>

* install grub
<pre>
grub-install --root-directory=/mnt /dev/sdb
</pre>

* shutdown system

* detach old disk

* move new disk to Primary Master (IDE)

* boot system with new disk

* reinstall grub one final time:
<pre>
update-grub
grub-install /dev/sda

-or-

dpkg-reconfigure grub-pc
</pre>

===TROUBLESHOOTING===

- at the blue grub menu, enter the edit mode (press 'e') and change the UUID=xxxx to /dev/sda1

- if you've forgotten to update the uuid, you can still boot the disk
<pre>
grub rescue>
grub rescue> set prefix=(hd0,1)/boot/grub
grub rescue> insmod ext2
grub rescue> set root=(hd0,1)
</pre>
(find out the kernel image name using ls, ls (hd0,1)/, ls (hd0,1)/boot)
<pre>
grub rescue> linux /boot/vmlinuz-3.16.0-4-686-pae root=UUID=xxxxx ro recovery nomodeset
grub rescue> initrd /boot/initrd.img-3.16.0-4-686-pae
grub rescue> boot
</pre>
(instead of the UUID you can also use 'root=/dev/sda1')
(you can also remove 'ro recovery nomodeset')

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Admin at 03:44, 20 January 2016