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5-6] What kind of HD should I use with CD-R? Must it be AV-rated?




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This article is from the CD-Recordable FAQ, by Andy McFadden (fadden@fadden.com) with numerous contributions by others.

5-6] What kind of HD should I use with CD-R? Must it be AV-rated?

(2002/01/11)

Any recent hard drive will work fine. Back in 1998 this was the subject
of some concern, but modern drives are much faster and more intelligent.

There is a fair amount of confusion over what exactly is an "AV drive". A
brief discussion is presented here; for more information see Bertel
Schmitt's article at http://www.fadden.com/doc/avdrive.txt.

The most important issue is thermal recalibration. Older hard drives
would pause for up to half a second (or even up to a full second, depending
on who you believe) every so often to adjust the head positioning to the
current operating temperature. For most applications this goes unnoticed,
but when recording a CD-R you must write the current track to completion
without interruption. "AV" drives deal with the problem in a way that
doesn't disrupt the disk activity.

A drive that does a quick thermal recalibration is acceptable if the system
is otherwise fast enough or the buffer in the CD-R unit or in the recording
software is large enough (early drives had only 64KB, while current drives
have 2MB or 4MB, making it much less of an issue). You need to be sure
that the recorder's write buffer won't empty during the recal period, or
you'll end up with a buffer underrun.

Most modern hard drives do smart thermal recalibration. This really isn't
something you need to worry about anymore.

What separated a Seagate Barracuda from a Seagate Barracuda AV is that the
latter is tuned for AV performance. This was simply a software change
that affected cache allocation algorithms, error correction, and other
SCSI parameters to get better performance for transfers of large blocks
of contiguous data. These sorts of optimizations were very important for
digital video running at a few MB/sec, back when that was close to the
maximum capability of the drives.

If you think AV optimizations will help you, you should take a look at
"Dr. SCSI" at http://www.scsitools.com/.


 

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