(cache)[SOLVED] How to reload a CD/DVD without physically opening the disc tray?

exerceo · 02-20-2024, 04:27 AM

After burning an optical disc (CD/DVD/Blu-ray) using K3b with the option not to open the tray, Linux still thinks that a blank disc is inserted.

lsblk still lists the disc as "2K" size:

Code:

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sr0          11:0    1     2K  0 rom

Mounting the disc fails:

Code:

mount: /media/username/RAM/disc: wrong fs type, bad option, bad superblock on /dev/sr0, missing codepage or helper program, or other error.

However, K3b correctly shows the disc label. This means that the optical drive and K3b is aware that the disc contains data, but the Linux system outside K3b is unaware of it, until the tray is physically opened and closed.

On Windows, writing to the disc without opening the tray works. Windows Explorer shows the files immediately after finishing.

Is there any way to reload an optical disc on Linux without physically opening the tray? How to make Linux "aware" of the new data on the disc without physically reloading the tray?

Side note: In the title of this post, I used "CD/DVD" instead of "optical disc" or "Blu-ray disc" because "CD/DVD" is the most widely understood, and "disc" can be confused with "hard disk".

And to the criers of "optical discs are obsolete!!1!1!", watch: https://www.youtube.com/watch?v=qbxaPc2Xf5M

lvm_ · 02-20-2024, 06:20 AM

partprobe?

exerceo · 02-20-2024, 10:25 AM

Quote:

Originally Posted by lvm_

partprobe?

Didn't work. It caused the optical drive to spin up, but it still appears as "2K".

Code:

$ sudo partprobe /dev/sr0; lsblk /dev/sr0
Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only.
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sr0   11:0    1   2K  0 rom

kilgoretrout · 02-21-2024, 11:07 AM

Your lsblk output indicates the optical drive is not mounted. So just mount it with:

Code:

$ sudo mount /dev/sr0 <mountpoint>

Once mounted, the data on the drive should be accessible without having to eject the optical media. Note, the mount command must be run with admin privileges. Also, if you are writing cd audio to the disk, i.e. you are making a music cd, the disk will not be mountable with the mount command as cd audio disks have no filesystem.

jayjwa · 02-21-2024, 12:11 PM

Maybe rescan the bus? Assuming sr0 as proper device. You should also verify that the disk wrote correctly to rule that out.

Code:

echo "1" > /sys/class/block/sr0/device/rescan

exerceo · Today, 06:20 AM

"Please note that this thread has not been replied to in over 6 months. Please ensure your reply is still relevant and timely." - You bet it is!

The solution is:

Code:

# lsblk /dev/sr0 
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sr0   11:0    1   2K  0 rom  
# cd /sys/bus/scsi/drivers/sr
# ls
3:0:0:0  bind  uevent  unbind
# echo 3:0:0:0 >unbind
# echo 3:0:0:0 >bind
# lsblk /dev/sr0
NAME MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sr0   11:0    1 46,6G  0 rom

(Requires root access, hence the hash symbols.)

Voilà! There you have it.

Credits go out to Guy Bernard. A bug report he posted to Debian in 2020 contained the solution.

#970805 - Unable to mount after burning a CD with wodim - Debian Bug report logs

exerceo · Today, 07:02 AM

Quote:

Originally Posted by exerceo

After burning an optical disc (CD/DVD/Blu-ray) using K3b

Oh, by the way, I don't use that anymore. I use command-line tools now because they don't do undesirable stuff in the background like automatically initiating a checksumming of a disc image (IMG or ISO file) when I didn't ask for it. And they can be controlled through functions and scripts.

Command-line tools also have options that are not shown in the graphical interface of k3b, such as spare:none on growisofs and without_spare on xorriso, which doubles the writing speed on Blu-ray by deactivating defect management. Defect management is unnecessary for DAO (disc-at-once) writing a brand new disc. Not to be confused with error correction while reading data, which is always on because there is no reason for it not to be in use.