CD-R: Why suddenly unreadable?


#1

I burned a data CD-R (brand: DataLife™) in 2012. I have a backup, but I am just inquisitive about what happened.
In 2014, it was perfectly readable after not being used for two years.
Then, I read the disc. It worked fine. On the next day, it was suddenly unreadable. The computer drive failed recognising it.

An audio CD player test confirms, that the data length is 41 minutes. The TOC is readable, but playback won’t start. An audio CD player usually plays data CDs muted.
If I jump to the position of 1 minute or 41 minutes with the CDDA player, it works. Perfectly. Rewinding back from 1 minute works back to 4 seconds.

This suggests, that the first 4 seconds worth of computer data (which probably contained the master file table) is destroyed.

The CD has no physical scratches at all. No disc rot. No damage. And bitfading should not happen from one day to another.
But: It was burned at full speed (×24 CAV) using a slim laptop drive, which could cause low quality. But then, why are exactly these 4 first seconds (mathematically equals around 300 sectors) of data demolished?


#2

Simply you was lucky the first time that the drive was able to focus on the disc.

Sometimes there is concentration of errors (spikes of E21 or E22) at the begging of the disc due to the increased vibration when the recording process begins. As the time passes and degradation takes place suddenly those errors become more problematic for some drives to handle.


#3

Thank you for your information.
I wonder, why a disc burned in 2012 was readable in 2014 and unreadable one day later by ALL drives.