I am trying to create an image of /dev/sda1
on an external drive using the "Disks" utility. When I select "Create disk image," set everything up and click "Start creating..." it asks for the root password, saying it wants to unmount /dev/sda1
. It seems like possibly not a good idea to unmount the main system disk. Is this what it's supposed to do?
2 Answers
Disks alias gnome-disks
Yes, this is what you are supposed to do.
The source:
- When cloning a drive, the source drive in the cloning process should have no mounted partition.
- When cloning a partition, it should not be mounted.
The target:
- When cloning to a target drive or partition, the same rules apply to the target (as decribed for the source).
- When creating an image (or compressed image), you write it as a file to a file system in a mounted partition.
And you should boot from a 'third' drive, for example an Ubuntu live USB pendrive, and write the image to a second drive, for example a HDD or SSD connected via USB.
Clonezilla
An alternative is to use Clonezilla. I would recommend it, because it can recognize which blocks are used in the file systems (of the partitions), and skip copying the free blocks. This reduces the work and makes the process faster.
Download a Clonezilla iso file, create a boot drive (CD disk, USB pendrive or memory card) and boot from it. Then you can use Clonezilla's wizard-style menu system to clone the whole drive or 'only' some partition(s) to another drive or in your case create an image.
The Clonezilla image is a directory with a number of files, and you can use Clonezilla to restore from that image to another drive/partition of at least the same size as the original drive/partition.
Link
'Disks' as well as the command line tool dd
are cloning tools, so the following link is relevant,
Use dd
instead:
sudo dd if=/dev/sda1 of=/path/to/backup-file bs=1M
Use another partition to store your backup.