How to shrink, clone an entire Linux disk and boot it?

Question

I had an Ubuntu 14.04 running on a 1024 GB disk (disk A), which only used up to 130 GB spaces. I want to clone it to a 256 GB SSD disk ( disk B ). But failed.

I used gparted to shrink the partitions on disk A to be only about 180 GB for the preparation for disk B successfully.

Can you tell me where I was wrong?

1) restore the partition table

I did backup the partition table of disk A.

└──╼ $ sudo sfdisk -d /dev/sda
# partition table of /dev/sda
unit: sectors

/dev/sda1 : start=     2048, size=   997376, Id=83, bootable
/dev/sda2 : start=   999424, size= 15624192, Id=82
/dev/sda3 : start= 16623616, size=337020928, Id=83
/dev/sda4 : start=        0, size=        0, Id= 0

Tips

/dev/sda1 for /boot, /dev/sda2 for swap, /dev/sda3 for /.

Save partition table

sudo sfdisk -d /dev/sda > partition.table

Then I tried to restore the partition table to disk B ( /dev/sdc in this scenario ).

I replaced sda with sdc in file partition.table. Then it looks like:

# partition table of /dev/sdc
unit: sectors

/dev/sdc1 : start=     2048, size=   997376, Id=83, bootable
/dev/sdc2 : start=   999424, size= 15624192, Id=82
/dev/sdc3 : start= 16623616, size=337020928, Id=83
/dev/sdc4 : start=        0, size=        0, Id= 0

Then do the restore successfully.

sudo sfdisk /dev/sdc < partition.table

2) migrating disk partition content

sudo dd if=/dev/sda1 of=/dev/sdc1

sudo dd if=/dev/sda2 of=/dev/sdc2

sudo dd if=/dev/sda3 of=/dev/sdc3

After migration, those partitions on /dev/sdc can be mounted and viewed.

Failure

But if I plugged the SSD disk (disk B) into my laptop, it would not boot up after some Thinkpad BIOS output. No error came out but a blinking cursor...

I bet the BIOS even did not detect the /boot on disk B when doing booting.

Can you help me? Many thanks!

---

update

Some one suggested me to use grub-install /dev/sdc to do the trick.

I searched what grub-install is capable -- link Let me try. And I am pretty sure disk A ( had MBR installed ).

---

Update

After doing dd if=/dev/sda of=/dev/sdc bs=512 count=1 , insert disk B only, it's still the same blinking cursor. Nothing really after BIOS.

After doing grub-install --boot-directory=/mnt/mypartition/boot /dev/sdc I went to boot it up, only disk B.

But grub console came out . And reported

---

Update

Now it is working!!!

Here's how I did it, on the PC running disk A as OS and the disk B (/dev/sdc) as a USB hard drive.

sudo mount /dev/sdc3 /mnt
sudo mount /dev/sdc1 /mnt/boot

sudo grub-install --boot-directory=/mnt/boot /dev/sdc3

Then went to the /mnt/boot/grub/grub.cfg, I did replaced 2 things in file grub.cfg. (remember to give write permission to the file grub.cfg)

replace hd1 with hd0

replace /dev/sdc3 with /dev/sda3

Then save the file. -> Power off computer -> Insert disk B via SATA and take out disk A forever. -> Boot -> See grub error but still boot up

If you met error Error: invalid environment block. Press any key to continue, please check this to solve it. Press any key will boot your system. https://askubuntu.com/questions/191852/error-invalid-environment-block-press-any-key-to-continue

sudo -i

Then, run each command, one-by-one.

cd /boot/grub
rm grubenv
grub-editenv grubenv create
grub-editenv grubenv set default=0
grub-editenv grubenv list
update-grub

Now go rebooting, it will work!

This is how I shrank my 1024GB disk hard drive and migrated the entire system to a new 256GB SSD disk.

Answer 1

I am not familiar with sfdisk, but you could accomplish the same thing, partition table AND MBR back up using dd.

This was in my notes and I am not the author...

Backing up the MBR

The MBR is stored in the the first 512 bytes of the disk. It consist of 3 parts:

• The first 446 bytes contain the boot loader.
• The next 64 bytes contain the partition table (4 entries of 16 bytes each, one entry for each primary partition).
• The last 2 bytes contain an identifier

Clone the MBR as mbr.img:

dd if=/dev/sdX of=/path/mbr_file.img bs=512 count=1

Clone partition as pX.img

dd if=/dev/sdX of=/path/pX.img bs=1024

Restore the MBR to new disk

dd if=/path/mbr_file.img of=/dev/sdY bs=512

Restore Partition to new disk

dd if=/path/pX.img of=/dev/sdX bs=1024

OR

You could use clonezilla to make an image of the OS and restore it on a disk that already has the partitions created.

This way you might need to reinstall grub on the new disk

grub-install

grub-mkconfig

and set your swap partition in the 'new' OS.

mkswap

swapon