Date: Tue, 17 Mar 1998 16:31:11 -0500 (EST) From: Open Systems Networking <opsys@mail.webspan.net> To: Rob Schofield <schofiel@xs4all.nl> Cc: freebsd-hardware@FreeBSD.ORG Subject: Re: CD-R and Scanner recomendations for CD archiving of records? Message-ID: <Pine.BSF.3.95.980317162415.10950H-100000@orion.webspan.net> In-Reply-To: <350EE7DC.78D6@xs4all.nl>
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On Tue, 17 Mar 1998, Rob Schofield wrote:
> 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,
What you say above is probably true. But I think you have just backed up
my 2nd post about using a more reliable media than CD-R like punchcards.
I mean look at all the work involved in your steps above to do archiving.
reliably :)
It would be MUCH easier, and more reliable for me anyway to just grab a
SCSI DAT drive and archive away. I dont mean to tear down your obvious
love of CD-R, but your guidelines are like that of windows. You can run
windows reliably! Just only run it on tuesdays, BUT you have to have a
black cat ON the monitor, AND it has to be past sunset!! And some holy
water never hurts :)
I still say after my CD-R problems it's a better choice to just use a SCSI
DAT tape drive. More storage, and will last far longer in my opinion than
CD-R which is aparently quite finicky for more people than just myself.
But as I said it's just my opinion! :)
FLAME ON!
Chris
--
"I am closed minded. It keeps the rain out." <---- True to my word!
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