Unable to Read DVD

Question

Unable to Read DVD

I am trying to transfer backup files stored on optical discs to the cloud, and I am able to read some of them, but not others, even though they are the same brand & type of disc. When I insert the disc, I'm given the option to initialize or launch certain apps - Finder, Music, Disk Utility, etc. I burned the disc with the same external DVD drive (USB), just with an earlier version of MacOS. The strange part is that Disc Utility is showing it as an 8.8 TB disc, yet the maximum capacity for any optical media, even double-sided dual-layer discs is around 8.5 GB. More confounding is that I was definitely able to read the disc in previous versions of MacOS, though I couldn't say for sure under which version the disc first became unreadable.

I'm sure there is at least a small chance I could recover the files with special software or even bringing it to a specialist, but before I bother considering any of those options:

Is there a way to browse the file system to see if there is anything worth trying to recover?
Is there any reason the same type of disc, burned in the same way, might be readable with a modern version of MacOS (Monterey) while another would not be?

Thanks for any ideas...

MacBook Pro 13″, macOS 12.6

Posted on Oct 17, 2023 7:02 AM

Reply

Answer 1

Top-ranking reply

HWTech

Level 9

59,762 points

Oct 17, 2023 9:21 AM in response to adamfromtempe

CDs/DVDs do degrade over time and are not the long term storage solutions that were advertised years ago. The laser on the optical drive may also be weakening which could lead to trouble reading certain discs. It is possible the laser is dirty...they used to make a special cleaning disc to try to wipe off very light build up of dust, but they are not meant to clean really dirty ones.

Plus CDs & DVDs had several methods which could have been used when creating them which could explain other reasons why some work & some do not. If a burning session was not closed, or if there were multiple sessions, this could cause some issues when accessed with another OS or computer.

If you cannot mount the disc, then you could try using a data recovery app such as Data Rescue, or Stellar Data Recovery, etc.

Reply

Answer 2

Kurt Lang

Level 9

61,406 points

Oct 17, 2023 9:26 AM in response to adamfromtempe

To add one more to HWTech's excellent post.

It may also depend on how old these disks are. If they're really old and were written in the original Apple HFS format, that would be why you can't read them in Monterey. Mojave was the last version of macOS that could read an HFS disk. After that, an Apple format must be HFS+ (Mac OS Extended), or APFS.

Reply

Answer 3

HWTech

Level 9

59,762 points

Oct 17, 2023 8:42 PM in response to Kurt Lang

Kurt Lang wrote:

It may also depend on how old these disks are. If they're really old and were written in the original Apple HFS format, that would be why you can't read them in Monterey. Mojave was the last version of macOS that could read an HFS disk. After that, an Apple format must be HFS+ (Mac OS Extended), or APFS.

I forgot to consider that, good catch!

Reply

Unable to Read DVD

Similar questions