Permission Denied Using dd to Clone Main Drive – Troubleshooting Guide

cloningddinstallation

So I'm trying to clone the setup of one computer to 4 identical machines on the same network. I don't fancy the idea of meddling with the insides of the computer, so I'm following the method outlined here

However, whenever I try the method outlined in the accepted answer, I get
dd: opening 'dev/sda1':Permission denied

Since the drive I'm cloning is my main partition, I'm running both machines off of live CDs. I thought it might not be working because I can't clone the drive when it's mounted, but running umount /dev/sda1 / says it's not mounted.

I'm not 100% set on using this particular method, if there's some other way that would also get the job done.

Best Answer

Try this: press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo -i

That will give you a root shell, that way it'll all run as root.

Cloning from one drive to another drive

What you describe in your question works in general.

sudo dd if=/dev/sdx of=/dev/sdy bs=4096 && sync

I have done it successfully with USB pendrives as well as with HDDs and SSDs.

But there are several things that can make it go wrong.

The target drive must be at least as big as the source drive. Not one single byte smaller. It is not enough that the drives have the same nominal size, for example 16 GB. You can check with
```
sudo parted /dev/sdx u b p
sudo parted /dev/sdy u b p
```
where x and y should be replaced with the device letters for the source and target drives, and u b makes the output in bytes and p tells parted to print (to standard output).
If there is a GUID partition table, GPT, (and not an old style MSDOS partition table), and the drives have not exactly the same size, you must repair the backup partition table at the tail end of the drive. The previous command lines with parted will also show the partition table. You can use gdisk for this repair job.
If the physical sector sizes are different between the source and target drives, there will also be problems. Small and old drives have usually 512 bytes physical sectors, but some new drives (medium size and huge size) sometimes have 4096 bytes physical sectors. This can cause problems after cloning, and it is probably better the install a fresh system in the new drive and transfer the files, that you want into the new drive (copy on the file level instead of cloning on the drive level). The previous command lines with parted will also show the physical sector size.
Both the source drive and the target drive must be healthy. If there is a bad sector (physical sector), the corresponding data cannot be transferred for that particular location, and it may cause a problem (big or small, depending on what is stored in that location).
Please do not clone the drive that you have booted from. For example, boot from a Lubuntu live drive made from a Lubuntu iso file in order to clone from a drive with an installed Lubuntu system to some other drive.

No partition on the source drive and the target drive should be mounted. Unmount if some partition is mounted.
```
sudo umount /dev/sdxn
```
where x is the device letter and n is the partition number.
Cloning with dd is risky, because it does what you tell it to do without any questions. A minor typing error is enough to make it overwrite the family pictures. For this reason it is better to use a tool which helps you identify the target drive and has a final checkpoint, where you can double-check that things will go right.
- in Linux you can use Disks alias gnome-disksor mkusb
- in Windows you can use Win32 Disk Imager.
You can also clone with Clonezilla. Boot a USB pendrive or DVD disk made from a stable clonezilla.iso file. This is safer than dd because of several checkpoints and questions, and faster because Clonezilla is smart enough to only copy used blocks (and skip free blocks) of the file systems. This makes a big difference if a file system is far from full.
And last but not least, you must let the process finish properly and let the system flush the buffers to the target drive. This is why it is important to run sync and wait until it finishes, and the terminal window returns to prompt.

Cloning via an image file

What is described here is also relevant if you clone in an indirect way by creating an image file from the source drive and restore from the image file to the target drive.

After the cloning, connect only one drive to the computer

If there are writable file systems, you must not boot a computer with both the source and target (of the cloning) connected. These drives have identical data, and there will probably be confusion, which can destroy one or both of the drives.

So boot into either the original (source) drive or into the cloned copy (target) drive, and keep the other drive disconnected (unplugged).

Encryption Cryptsetup Cloning – Fix Encrypted Drive Cloning Resizing Partitions Problem

I'll need to test this on a completely clean set of circumstances but running these commands at the end of the above described procedure seems to work. I will update this solution if I hit any more snags.

sudo parted
(parted) print                                                         
(parted) resizepart
Partition number? 2
End?  [32.0GB]? 100%
(parted) print                                                
(parted) quit

Best Answer

Related Solutions

Ubuntu – Lubuntu 18.10 x64 installed on USB stick clone to usb stick 2

Cloning from one drive to another drive

Cloning via an image file

After the cloning, connect only one drive to the computer

Encryption Cryptsetup Cloning – Fix Encrypted Drive Cloning Resizing Partitions Problem

Related Question