Date: Sat, 10 Jul 2004 17:47:46 +0400 (MSD) From: Dmitry Morozovsky <marck@rinet.ru> To: Jean-Sebastien Roy <js@jeannot.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Silent errors when reading CDs Message-ID: <20040710174546.T85065@woozle.rinet.ru> In-Reply-To: <40EF172C.7020508@jeannot.org> References: <40EF172C.7020508@jeannot.org>
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Hi there, On Sat, 10 Jul 2004, Jean-Sebastien Roy wrote: JR> I'm currently using FreeBSD 4.10 on an HP D530 SFF. JR> The system is perfectly stable except for the following problem JR> I'm unable to understand : JR> JR> When I mount a cdrom (mount /cdrom), then calculate the MD5 hash JR> of a big file on a CD (md5 /cdrom/bigfile), the results are often random: JR> unmounting, mounting again and calculating again the MD5 often result in JR> a different value. What disturb me the most is that absolutely no errors JR> are reported in any log (no read errors for example). JR> JR> I thought the CDROM reader, a LITE-ON LTR-48327S PQS3, was the culprit, JR> so I replaced it with a PLEXTOR DVDR PX-712A and got the exact same JR> results (i.e. random MD5 values). I checked the RAM using memtest and JR> got no errors. The problem does not occur for files on the harddisk. JR> JR> hw.ata.atapi_dma is set since both drives support it and it seems to be JR> required for proper CD/DVD burning. The CD drive is the master on its JR> own ATA bus. JR> JR> While the problem occurs on multiple CDs (mostly RW), to my surprise, I JR> was not able to reproduce the problem by reading big files on DVDs. JR> JR> Could someone provide me a hint on what to check next or how to fix this JR> problem ? Can errors on CDs generate such a behavior ? What if you copy that big file from CD to HD twice (possibly with unmounting/remounting in the middle) and check MD5s there? Testing your memory with memtest86.com's test would also be helpful to eliminate RAM issues. Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------
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