Problems reading CDRW after writing

[Malcolm Kay]

On Wed, 4 Jan 2006 03:37 am, Marc Evans wrote:
> Hello -
>
> I am running FreeBSD 6.0-STABLE as of Dec-15-2005 on a P4
> system. I have a CDRW drive attached, which identifies as
> follows:
>
>  	acd0: CDRW <CD-RW 52X24/K.NC> at ata1-slave UDMA33
>
> I wish to use this device to produce CDRW backup disks
> periodically. I use the following commands to produce the
> backup:
>
>  	burncd erase
>  	sleep 2		# needed to avoid READY error
>  	tar czf - ... | burncd data - fixate
>
> This appears to work fine, from the perspective of the output
> of the commands, e.g. I see output like:
>
> blanking CD - 100 % done
> next writeable LBA 0
> writing from stdin
> written this track 633420 KB total 633420 KB
> fixating CD, please wait..
>
> My problem is that attempts to read the data back, always
> fail:
>
> # tar tzf /dev/acd0
> tar: Error opening archive: Error reading '/dev/acd0':
> Input/output error # ls -l /dev/*cd*
> crw-r-----  1 root  operator    0,  93 Jan  3 10:33 /dev/acd0
> crw-r-----  1 root  operator    0, 127 Dec 30 14:26
> /dev/acd0t01
>
> No errors are shown in /var/log/messages.
>
> I have also tried writing an ISO9660 image and mounting it,
> with similar problems at mount time.
>
> The above said, I am able to create CD-R data disks and mount
> them or otherwise use them. I have tried several different
> CD-RW media, and played with -s (the media is rated as 12x),
> but have observed no changes.
>
> Can anyone suggest solutions?
>

This raises a number of questions:-
* Can the RW disks you have written be read in some other drive?
* Can you read RW disks written somewhere else?

A pure shot in the dark -- but I suspect the read on your drive 
may not be sensitive enough to read RW disks.

Of course if it can write them one would expect it is designed to 
be able to read them -- but it may be out of spec. or have 
deteriorated since manufacture.

Malcolm