ab2 - About some old DVD-R data

ab2 - About some old DVD-R data

First, on the previous post, "ab1" & "abo", Google/Blogger has recovered the lost post of Thursday May 12 2011. I got all excited for nothing. One should know better, that Google, with all their power and resources would have redundant data capabilities. (Thank you Google). One thing I didn't notice was the day I posted "ab1" happened to be Friday the 13th! This year, it is the only Friday the 13th on the calendar. Is this a coincidence? (There are no coincidences.). There is a small quirk in my "ab0" post's tag/label. The tag "cd-rom" now has two funny characters next to it:

Summary, Google/Blogger has efficiently and professionally dealt with the data loss and data recovery.

For today's post, "ab2", I want to document a similar issue as post "ab0", only that instead of data loss from a Cd-rom, I want to talk about data loss from a DVD-R disc. I have discovered 3 of my DVD-R discs are unreadable in my DVD-RW drive. These discs are approximately 3 and a half years old. When I burned them originally, I immediately verified the data after the burn. Recently, once inserted into the drive, the discs spins for 10 - 20 secconds, and then Windows thinks the discs are blank. The good news is that on a different computer & drive, the disc(s) becomes readable. I have been able therefore to recover this data. I don't know what to attribute this loss to. Perhaps one of my drive's has faulty/different laser alignment. Could it be due to DVD-R rot? Is there such a phenonmenon?

ab1 - Will Yesterday's Blogger Post Return

ab1 - Will Yesterday's Blogger Post Return?
Yesterday, Thursday, May12.2011 just before lunch time (so, approximately 27 hrs ago), I posted a short essay discussing data loss due to aged cd-r media discs, i.e., "Cd-rot". Today, when I clicked on my "blogspot" or the post's permalink is: http://jianchomeshi.blogspot.com/2011/05/ab0.html , Blogger indicated that there is no such page. See the ScreenShot (sss):

A part of me thought I was becoming more insane than usual, because I remembered writing the post. After logging in & out to Blogger several times I went to the "dashboard" etc.. to see if my post was sent to "draft" status, but I could find no evidence.

Even as I write this, yesterday's post is still absent. (sss).


I am reassured after I searched for my post in Google, that evidence of its existence is shown.
.
Blogger-Buzz reassures posts' retrieval by explaining the technical difficulties: http://buzz.blogger.com/2011/05/blogger-is-back.html . .
Anyway, I am keeping my fingers crossed and I hope yesterday's post will return. Briefly the post was about how some of my 10 year old cd-r discs have deteriorated and the data/files is either partially or totally corrupt. I bear no hard-feelings against Blogger as they provide this wonderful service for free. I am not surprised that digital information is so fragile. I was somewhat stunned when I looked at my Blogspot and discovered my post was missing.

ab0 - A Case of Cd Rot

ab0 - A Case of Cd Rot

Recently, I have experienced first hand cd-rom degradation. Some data cds (homemade), 10 years ago have corrupt files or the entire disc is unreadable by the computer's optical drive. Four or five of my discs have 10-20% files unreadable. One disc was very poor. It refused to be read in 4 different optical drives! This one is a brand-name disc. I'm not going to reveal the brand, but I am very happy with their equipment and their media. Disc rot, I believe happens to any/all brands of media. (It may happen more with generic, no-name discs, but I can't prove this.)

I had read about disc rot in a computer magazine 5+ (?) years ago. The way I understand it: The bits degrade with time and your data becomes corrupt. The computer will be unable to read it &/or give an error message of "cyclic redundancy check error" (or similar). Blank optical discs have a layer of pigment/dye/ink sandwiched in some type of plastic/polymer. The cd-writer laser(s) burn concaves into this dye which is later read as data (ie 1's and 0's). Over time, the dye degrades and so does you data.
One doesn't believe they are susceptible to Cd rot until it happens. It also happened with my commercial discs; but fortunately the corrupt data was only about 5% unreadable. (Perhaps commercial discs are manufactured differently or with different materials.)
Again the moral of the story is to make regular backups of your digital data.
A friend purchased some archival quality cd-r's designed for digital photographs, but they use it for their data. I'm assuming/hoping that these cd-r's would degrade slower than regular quality cd-r's. So far not enough time has passed for an opinion to be made.