On Jan 5, 2008, at 2:58 PM, Rick Thomas wrote:
On Jan 5, 2008, at 10:16 AM, Douglas A. Tutty wrote:On Sat, Jan 05, 2008 at 02:53:45AM -0500, Rick Thomas wrote:As a registered pack-rat, I've got a drawer full of similar old CD-Rs. If I get ambitious and I've got some free time, I'll try a bunchmore, just for fun...I wonder what cdck would show. It tests not only ability to read the files, but counts any otherwise silent errors as well. It also automates the reading every file process.OK. There seems to be a "cdck" package in Debian Etch. If I get ambitious and test (some of) the other CD-Rs in that drawer, I'll use cdck for the tests. Don't hold your breath for results, but if I do it, I'll post anything I find here.
Interesting... I tried cdck on two CDs:The first was a CD-RW I just wrote last night. It said it was "satisfactory". The longest time was on the order of 0.5 sec, and there were about a dozen of them, mostly near the beginning of the disk.
The second was one of my ten-year-old archive disks. It, cdck, said it was unacceptable, based on a couple of dozen unreadable sectors -- all at the end of the disk. The rest of the disk looked a lot like the first one, except that the maximum time was on the order of 0.7 sec, and there were only about a half-dozen of them, scattered near the beginning of the disk.
The "bad" sectors at the end of the disk obviously weren't in any files, so they don't affect the quality of the disk as an archive. I wonder what mechanism there is that only affects sectors at the end of the disk? Maybe the original drive that wrote it ten years ago put a few garbage sectors on each disk it wrote as part of the closing-out process??? Anybody know for sure?
Rick