How to back up optical disk in Linux

Creating a backup of an optical disk on a Linux system involves copying the disk's content into an ISO image file. This file serves as an exact digital replica of the optical disk, whether it’s a CD, DVD, or Blu-ray. This allows you to preserve and restore the data whenever needed. Using Linux terminal commands, you can efficiently generate this image, ensuring your data remains intact.

Before creating the ISO image, it is important to check the size of the optical disk. This ensures that you have enough available space in your target storage location. Accurate space management is essential to prevent interruptions during the backup process.

Once the disk size is verified and space is confirmed, you can proceed to create the image file. The dd command in Linux is commonly used for this task. It allows you to clone the optical disk into an ISO image, which can be stored or used to create another physical disk later.

1. Open the terminal on your Linux system.
2. Identify the device name of your 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

   The device name is typically something like sr0. The exact output may vary depending on your system configuration.

3. Insert the optical disk (CD, DVD, or Blu-ray) into the drive.
4. Check the disk size.

   $ 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. Ensure there is enough free space in the target location.

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

6. Use the dd command to create the ISO image of the disk.

   $ 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. Verify the integrity of the image by checking checksums.

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