Moving an installation, from one partition to another.

[edbarx]

So, you have a working installation, and for some reason, you want it transferred to another partition or to another disk possibly before a disk failure. I have done this several times, and the good news is that, it can be done and it should work.

Needless to state the obvious, if you are doing this due to an impending disk failure, the first thing is to make a backup of your installation.


The Procedure

1. Mount the partition containing the backup or the original installation. I will assume it is on /dev/sdb1. Again, for conformity, create a directory named sdb1 under /mnt.

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   mkdir /mnt/sdb1

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   mount /dev/sdb1 /mnt/sdb1

2. Do the preceding step for the destination partition, let us say, /dev/sda2.

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   mkdir /mnt/sda2

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   mount /dev/sda2 /mnt/sda2

3. Do the actual transfer. Some people use rsync, which is OK, however cp -a can do it implying there is no need of rsync for this procedure.

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   cp -a /mnt/sdb1/* /mnt/sda2/

   This will take some time as it will copy an entire installation.
4. Unmount the original partition i.e. sdb1.

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   umount /mnt/sdb1

5. With the destination partition still mounted, browse its newly copied file hierarchy to open /etc/fstab. Please note that this file needs root rights to be overwritten. In my case, I use vim, but you can choose any tool that can run with root privileges.

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   vim /mnt/sda2/etc/fstab

6. Find the line for the '/' directory. On this partitcular installation, it is:

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   # / was on /dev/sda2 during installation
   UUID=e56156fe-5848-1254-bf93-7132a1e54321   /   ext4    errors=remount-ro      0       1

7. Use the blkid command as root to determine the UUID of sda2, the destination. Copy it instead of the UUID shown in vim or your text editor. Save and exit.
8. Update grub-pc to update its menu items.
9. Unmount the partition.

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   Umount /mnt/sda2

Note:
If an installation is spanned over several partitions, the copy procedure has to be done for every partition in the installation being transferred. A multi-partition installation can also be transferred to a lesser number of partitions, provided, care is taken to copy the contents of every dropped mapped partition to their respective root folder, say /var, /home, /usr, etc.