burncd -- possible problem

[Shantanu Mahajan]

+++ Malcolm Kay [15-05-03 20:06 +0930]:
| 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

	try specifying the speed for writing.
	I generally use 16 or 20 for my 20x drive.

	# burncd -f /dev/acd1c -s 20 data cd.iso fixate

	Regards,
	Shantanu

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