Date: Sat, 10 Jul 2004 00:07:40 +0200 From: Jean-Sebastien Roy <js@jeannot.org> To: freebsd-hackers@freebsd.org Subject: Silent errors when reading CDs Message-ID: <40EF172C.7020508@jeannot.org>
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Hi ! (Following an advice from someone at freebsd-questions@, this is a repost of a question asked at freebsd-questions@) I'm currently using FreeBSD 4.10 on an HP D530 SFF. The system is perfectly stable except for the following problem I'm unable to understand : When I mount a cdrom (mount /cdrom), then calculate the MD5 hash of a big file on a CD (md5 /cdrom/bigfile), the results are often random: unmounting, mounting again and calculating again the MD5 often result in a different value. What disturb me the most is that absolutely no errors are reported in any log (no read errors for example). I thought the CDROM reader, a LITE-ON LTR-48327S PQS3, was the culprit, so I replaced it with a PLEXTOR DVDR PX-712A and got the exact same results (i.e. random MD5 values). I checked the RAM using memtest and got no errors. The problem does not occur for files on the harddisk. hw.ata.atapi_dma is set since both drives support it and it seems to be required for proper CD/DVD burning. The CD drive is the master on its own ATA bus. While the problem occurs on multiple CDs (mostly RW), to my surprise, I was not able to reproduce the problem by reading big files on DVDs. Could someone provide me a hint on what to check next or how to fix this problem ? Can errors on CDs generate such a behavior ? Thank you very much in advance, Regards, Jean-Sebastien
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