[rescue] cdrom woes again...

Curtis H. Wilbar Jr. rescue at hawkmountain.net
Sun Jun 8 10:04:34 CDT 2003

>From: "Geoffrey S. Mendelson" <gsm at mendelson.com>
>Subject: Re: [rescue] cdrom woes again... 
>Date: Sun, 8 Jun 2003 17:45:42 +0300 (IDT)
>Make sure that you do not have any old SCSI hard drives that do
>thermal recalibration on their own. If you do, and any drive on the
>controler recalibrates itself while you are burning the CD, it will go
>ok, but the the CD will have a bad spot on it.

All drives do thermal recalibration to my knowledge... and as far as I
know, they always do so on their own.  The speed of this process and
how the drive determines it needs a recal is the issue.... I've heard
that drives are now optimized based on read/write/etc to limit the
effects of a tcal.

How will the burn go OK ? ... if the tcal takes too long it will result
in a buffer underrun.... and any cdrecording program should catch that
(if it doesn't, I wouldn't use it to record even temporary data).

>Older drives require CD blanks with yellow dye. There are basicly two
>kinds of CD blanks, yellow or blue dye. Older drives do not read the
>blue dye CD's well.

A Yamaha 8X burner should handle reading and writing blue dye fine.

For dealing with older drives, the best thing I've found is to reduce
the write speed to 4X or even 2X... that makes for "cleaner" burns for
older readers (mainly cd-rom drives of the 1-4X generation) happier.

>Write the CD's at single speed. The faster speeds write smaller pits and
>sometimes it matters.

similar to what I just said... I usually find single speed is not necessary
though.... usually 2X or 4X does the magic depending on what you are 
writing on and what you intend to read it on....

>Turn of any anti-overrun software if you can. It works by stretching the
>gap between sectors to compensate for missing data. The gaps are within
>spec, but many older drives were not built to that spec. :-(

got any URLs on this.... I hadn't heard of this before... would like to
know more....  sounds odd.... this would have an effect on overall storage

>Consider cleaning the lens. I've repaired many a CD-ROM drive by using
>a head cleaning CD.

I've had mixed luck with head cleaning... guess most of the drives I've
cleaned were never dirty enough for that to be the problem.... and instead
I was looking at fubar'd drive syndrome....

>Geoffrey S. Mendelson gsm at mendelson.com 972-54-608-069
>Do sysadmins count networked sheep?
>rescue list - http://www.sunhelp.org/mailman/listinfo/rescue

-- Curt

Curtis Wilbar
Hawk Mountain Networks
rescue at hawkmountain.net

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