Date: Tue, 17 Mar 1998 22:15:08 +0100 From: Rob Schofield <schofiel@xs4all.nl> To: freebsd-hardware@FreeBSD.ORG Subject: Re: CD-R and Scanner recomendations for CD archiving of records? Message-ID: <350EE7DC.78D6@xs4all.nl> References: <199803171640.IAA11589@mail3.sirius.com>
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Comments: A significant number of "failures" in CD-R media are primarily due to operator problems (read the book!) If you mix IDE & SCSI read and write drives, you're GONNA have problems, so stick to SCSI & SCSI, IDE & IDE. The system basically should not be doing ANYTHING other than swap, so knock out EVERYTHING before you start. You need to have SIGNIFICANTLY more buffer space than is recommended (2-3X), and you are far better building an image on a hard disk rather than copy CD-CD. A bucket load of unecessarily free RAM helps too. Hard disks really need to to be in large block mode, or multi-sector; 7,200 RPM drives seem to be almost obligatory. DISABLE read cache on SCSI drives. Adjacent SCSI IDs are a good idea for the two drives involved in the read and write, with the Write drive at SCSI ID 6 (highest bus negotiation priority). It would not be possible to produce blanks without a conformal passivating layer below the foil coating; since it is vapour deposited gold with only a few microns thickness, this would simply rub off in your hand when you picked it up out of the jewel case (due to body fats and acids, and no, 10 um of gold is NOT sufficiently resistant to acid of any kind - think about the layer UNDER the pourous vapour deposit layer!) The quality of the lasers in many write drives is currently suspect; additionally, laser diodes do not take kindly to poorly-smoothed switched mode power supplies which are heavily loaded (as is typical in cheapo, 200W tower boxes). Reduce the number of cards in your box, and the number of drives. Alternatively, make sure you have a good power filter and a power supply of at least 320 W. What are you doing running a Pentium machine with under 300W, anyway? If anyone feels they have defective media, most of the reputable manufacturers offer some kind of replacement warranty; however, most of the time, there ISN'T anything wrong, so you'll probably be disappointed when yousend them back. Why, did you think the major manufacturers would risk their reputations by selling crap media? Ho ho Jolly Ho. If anyone has any "defective" CD-R blanks, then PLEASE send them to me, as I would find free disks to be a most attractive little perk! Sorry about the flame; this thread appears to be gaining mythical proportions, with a lot of hearsay entering reality as "fact". Please, ladies and gentlemen; do not attempt to accelerate the acceptance of myths. Research your facts properly before making unverifiable statements; also, bide your time and wait for the decent, second-generation WRITERS which is where the problem *really* lies. Rob Schofield M.Sc. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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