CD-Rs Can Go Bad

See also:  Bad_CD.JPG

While I believe that CD-Rs are the most reliable machine readable back 
up media presently available to people like me, they can go bad without 
the help of abuse.  The CD-R shown in the companion file was last 
written about a month ago.  It was last read within the last week and 
was OK then.  Today it is unreadable.  This is the first one like this 
I have seen.  Have others seen this?

I have always made at least two copies of my backups which are not kept 
in the same place.  I continued this practice when I started using 
CD-Rs for the purpose.  I'm very glad I did since the disk in question 
contains all my pix for a seven month period and I don't have a large 
enough drive to keep all my photos on line as well.

I coppied the files from the other backup to a new CD-R and will carry 
on.  Perhaps *really* valuable files should be in triplicate.