Date: Thu, 15 May 2003 19:16:03 +0530 From: Shantanu Mahajan <shantanoo@ieee.org> To: Malcolm Kay <Malcolm.Kay@internode.on.net> Cc: freebsd-questions@freebsd.org Subject: Re: burncd -- possible problem Message-ID: <20030515134603.GA687@dhumketu.homeunix.net> In-Reply-To: <200305152006.06346.Malcolm.Kay@internode.on.net> References: <200305142239.15266.Malcolm.Kay@internode.on.net> <20030514180803.GA594@dhumketu.homeunix.net> <200305152006.06346.Malcolm.Kay@internode.on.net>
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+++ 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 -- Madness has no purpose. Or reason. But it may have a goal.
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