burncd -- possible problem

[Malcolm Kay]

On Thu, 15 May 2003 03:38, Shantanu Mahajan wrote:
> +++ Malcolm Kay [freebsd] [14-05-03 22:39 +0930]:
> | I'm not sure whether I have a problem burning CD-Rs -- certainly
> | I don't understand what I observe.
> |
> | The OS is FreeBSD 4.7-release.
> |
> | I take a commercial CD-ROM and copy it as an image with:
> | # cp /dev/acd1c natins.cd
> | which creates the file natins.cd of around 673400*1024 bytes
> | without any apparent problem. (I can't remember the exact size
> | but was certainly a multiple of 1024).
> |
> | # md5 natins.cd
> | and
> | # cat /dev/acd1c | md5
> | produce identical results.
> |
> | Now inserting a blank CD-R:
> | # burncd -f /dev/acd1c data natins.cd fixate
> | runs apparently normally and without error.
> |
> | But now
> | # cat /dev/acd1c | md5
> | produces and IO error and a different checksum
> |
> | # cp /dev/acd1c natins.back
> | produces the same IO error and a file 8*1024 bytes
> | shorter than natins.cd.
> |
> | If I strip off the last 8k from natins.cd and compare the
> | result with natins.back I find they are the same.
> |
> | When I look at the last 8*1024 bytes stripped from natins.cd I
> | find these are all zero (ie NUL).
> |
> | Re-running burncd on a new CD-R blank repeats the result
> | exactly; i.e. IO error 8k short of the size of the original but the
> | rest matching.
> |
> | As a mounted cd9660 file system the copy appears normal and
> | the visible files test identical to those on the original.
> |
> | Questions:
> | Is what I'm observing normal when writing with burncd?
> | Do I have a hardware problem?
> | Is this due to some bug in burncd?
> |
> | Should I worry about this or just ignore?
> |
> | Malcolm Kay
> |
> | ------------------------------
>
> 	*suggestion* (works perfectly for me)
> 	instead of
> 	# cp /dev/acd1c natins.cd
> 	try
> 	# dd if=/dev/acd1c of=natins.cd bs=2048

Tried that except I forgot bs=2048 so it didn't work.
But file produced by cp looks fine and command executes without
reporting an error.

>
> 	and then
> 	# burncd -f /dev/acd1c data natins.cd fixate

This also appeared to go well -- no error reported.

>
>
> 	Also try mounting natins.cd with help of vnconfig

Did that; again no problems.

Problem only appears when I try to reread the completed 
new CD copy as a complete image. 

Then 'cat /dev/acd1c' and 'cp /dev/acd1c natins.back'
both report read errors and don't transfer what should be the last 8k bytes.
(I don't have the disk on hand at the moment but I'll try 'dd' on the written
 CD when I get to work tomorrow.)
 
However the created disk mounts OK and I am not able to find errors in it
as a mounted file system.

Have you written disks with burncd and then tried to read them as an image?

Shantanu,
Thanks for your thoughts and also yours, Eduardo.

Malcolm