Is possible to make the backup and the recovery root partition from one to the other?

Question

I have two Raspberry Pi boards. One is a (Pi 1) Model B and the other is a Pi 2 Model B.

The Pi 1 Model B is a new one from my friend. I had used the Pi 2 Model B for a long time.

I know the hardware ability better on Pi 2 B and I use it as a web sever. I consider to shift its "root partition" to the other Pi Model B.

Is this possible to make? I had used "gparted" to see it. There is a protection, a key in front of both boot and root partition.

I had cleaned up the root partition

sudo dd if=/dev/zero of=/dev/the_root_partition(i.e. sda2) bs=64

But, it is not workable.

My simple steps from my idea as below.

Step 1. Only burning the Pi 2 B image's root partition to a image by "dd" command

Step 2. Removing the Model B image's root partition.

Step 3. Buring the image which is saved by Step 1 to the Model B image.

Maybe there is a method to backup separately the boot partition and root partition to the computer. Then, using "dd" to recovery to boot partition and root partition to the empty sd card may be a possible way.

Note: My Pi 2 Model B has upgraded to Raspbian Stretch. In addition, both microSD cards are of same brand, with 32 GB of storage.

2018-04-19 ADDED MORE INFORMATION HERE: I use the "fdisk" to delete the rpi1 sd card's root partition and build a ext4 partition for itself. Then, I use "dd" to copy the rpi2 root partition only to the rpi1's sd card's ext4 empty partition. Then, I insert it to rpi1 board and get successfully booted. But, there is "kernel module failed" message when I boot the system. Even though I have root permission, I still get the message.

kernel module failed

Answer 1

Be very careful when using the dd command because a mistake of one character can destroy the wrong partition! Your dd command above has blanked (insert similar catastrophic word - destroyed, zeroed, obliterated) your root partition - is that what you intended?

The best way to do this in my opinion is to use rsync to transfer the contents of both the boot partition and the root partition. First, partition the second SD card with a boot partition (100M vfat) and a root partition (rest of SD card, ext4). Then use rsync to copy the contents. With file system copying you don't need to worry about the respective SD card sizes and it's also a lot faster.

For completeness here's how to use the dd command but bear in mind that you also need the boot partition as well because that contains the kernel that belongs with the root partition (specific kernel modules in /lib/modules). Also I recommend you use a larger SD card to transfer to. This is slow and dangerous so I highly recommend using rsync method above instead.

Burn your root partition to an image

This will put the image in the current directory. Replace rootpartition with your actual root partition device, eg. sda2.

sudo dd if=/dev/rootpartition of=root.img bs=1M

Burn the resulting image to a new SD card partition

With a new SD card that has been partitioned already, use the following command where newroot is the actual root partition on your new SD card, eg. sda2:

sudo dd if=root.img of=/dev/newroot bs=1M