How to backup optical disk in Linux

Optical disks used for operating system or game installer, or for media content such as Blu-ray, DVD, or CD are very prone to scratches. One way to protect the data is to create a backup copy of the optical disks as an image file. The process could then be reversed when you need to get your image back to an optical disk.

You can create ISO image from Blu-ray, DVD, or CD using dd at the terminal.

1. Launch terminal application.
2. Get device name of optical drive.

   $ dmesg | egrep -i 'cdrom|dvd|cd/rw|writer'
   [    6.834672] sr 3:0:0:0: [sr0] scsi3-mmc drive: 1x/1x writer dvd-ram cd/rw xa/form2 cdda tray
   [    6.835440] cdrom: Uniform CD-ROM driver Revision: 3.20

3. Insert optical media to drive.
4. Check size of optical media.

   $ fdisk -l /dev/sr0
   Disk /dev/sr0: 748 MiB, 784334848 bytes, 382976 sectors
   Disk model: VMware SATA CD01
   Units: sectors of 1 * 2048 = 2048 bytes
   Sector size (logical/physical): 2048 bytes / 2048 bytes
   I/O size (minimum/optimal): 2048 bytes / 2048 bytes
   Disklabel type: dos
   Disk identifier: 0x73a9f942
   
   Device     Boot   Start     End Sectors  Size Id Type
   /dev/sr0p1 *          0 1531903 1531904  2.9G  0 Empty
   /dev/sr0p2      1215132 1222619    7488 14.6M ef EFI (FAT-12/16/32)

5. Check available size of target location.

   $ df -h /home/user/
   Filesystem      Size  Used Avail Use% Mounted on
   /dev/sda2        20G  5.2G   14G  28% /

6. Clone CD/DVD/Blu-ray disk to an image file using dd.

   $ dd if=/dev/sr0 of=/home/user/cdimage.iso status=progress
   757838336 bytes (758 MB, 723 MiB) copied, 24 s, 31.6 MB/s
   1531904+0 records in
   1531904+0 records out
   784334848 bytes (784 MB, 748 MiB) copied, 24.5369 s, 32.0 MB/s

7. Check checksum of both optical media and image to confirm.

   $ md5sum /dev/sr0 /home/user/cdimage.iso
   9a659c92b961ef46f5c0fdc04b9269a6  /dev/sr0
   9a659c92b961ef46f5c0fdc04b9269a6  /home/user/cdimage.iso