Date: Thu, 15 May 2003 20:06:06 +0930 From: Malcolm Kay <Malcolm.Kay@internode.on.net> To: Shantanu Mahajan <freebsd@dhumketu.cjb.net> Cc: freebsd-questions@freebsd.org Subject: Re: burncd -- possible problem Message-ID: <200305152006.06346.Malcolm.Kay@internode.on.net> In-Reply-To: <20030514180803.GA594@dhumketu.homeunix.net> References: <200305142239.15266.Malcolm.Kay@internode.on.net> <20030514180803.GA594@dhumketu.homeunix.net>
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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 > | > | ------------------------------ > > =09*suggestion* (works perfectly for me) > =09instead of > =09# cp /dev/acd1c natins.cd > =09try > =09# dd if=3D/dev/acd1c of=3Dnatins.cd bs=3D2048 Tried that except I forgot bs=3D2048 so it didn't work. But file produced by cp looks fine and command executes without reporting an error. > > =09and then > =09# burncd -f /dev/acd1c data natins.cd fixate This also appeared to go well -- no error reported. > > > =09Also try mounting natins.cd with help of vnconfig Did that; again no problems. Problem only appears when I try to reread the completed=20 new CD copy as a complete image.=20 Then 'cat /dev/acd1c' and 'cp /dev/acd1c natins.back' both report read errors and don't transfer what should be the last 8k byt= es. (I don't have the disk on hand at the moment but I'll try 'dd' on the wri= tten CD when I get to work tomorrow.) =20 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 imag= e? Shantanu, Thanks for your thoughts and also yours, Eduardo. Malcolm
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