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I am wondering how fast the current 2011/2010 era macs spin the optical media. I'm talking about real physical speeds even if it is complicated.

Angular velocity is fine, linear velocity is fine - the radius is fixed, so the math is easy.

If you can address both slot load and tray loading or go into details how the speeds vary, that would be very nice.

I am also curious of the read speed is different than the burn speed for writeable media of the various types.

Some times you can specify 1x or 8x - but don't know what is the "normal" burn speed. My understanding is they employ zoned constant linear velocity (ZCLV) but I don't see a good reference for hardware that is shipping presently that goes into any detail what 8x actually means.

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It turns out this is pretty complicated. I'm looking for the maximum speed - whether it's at the start or the end of the process. Also - it looks like the data rates are usually three fold - (write-once data rate, re-write data rate, and read-only data rate) 12x/10x/32x for example. –  bmike Aug 15 '11 at 21:46
    
Just out of curiosity, why do you want to know the answer to this (which might be a silly question for me to ask after spending absurdly long trying to figure out the answer, with no motivation myself besides the fact that you asked...)? –  Daniel Lawson Sep 2 '11 at 5:09
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I want to know at a deep level exactly how the motor spins physically. On an inner track - does is spin slower than it "could" to keep the stresses on the outer part of the plastic low? Record players are easy - there are three common speeds. DVD/CD appear to be much more nuanced in how they spin the bits physically. I didn't have a good handle on what the data rates meant and how they varied based on where the laser was radially as well as which operation was being undertaken. –  bmike Sep 2 '11 at 13:23
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3 Answers 3

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According to ISO/IEC INTERNATIONAL STANDARD 10149 (Second edition 1995-07-15), which is the basis for the "1x" speed, the linear velocity at whatever point on the disc is being read needs to be between 1.2 and 1.4 meters per second. That would translate into a different RPMs at different parts of the disc.

A back of the envelope calculation suggests that the fastest a drive in a modern MacBook Pro would spin the disc would be during 24x read at the center of the disc; that would be around 12,000 revolutions per minute.

The full text of the standard is downloadable for free at http://standards.iso.org/ittf/PubliclyAvailableStandards/s025869_ISO_IEC_10149_1995(E).zip

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I've been digging and it looks like using that spec isn't applicable at higher data rates. See here where they talk about exceeding 10,000 rpm between 48x and 52x speeds. –  bmike Aug 15 '11 at 21:57
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Tray loading CD drives are the fastest, back in 2004 or so I had a 52x CD-RW drive (10,400 RPM) and it looks like they still make them. The fastest drive I see on the Apple website now is the 32x drive in the Mac Pro which tops out at 4,800RPM.

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It depends on what you're doing:

8x slot-loading SuperDrive (DVD±R DL/DVD±RW/CD-RW)

Maximum write: 8x DVD-R, DVD+R; 4x DVD-R DL (double layer), DVD+R DL (double layer), DVD-RW, DVD+RW; 24x CD-R; 10x CD-RW

Maximum read: 8x DVD-R, DVD+R, DVD-ROM; 6x DVD-ROM (double layer DVD-9), DVD-R DL (double layer), DVD+R DL (double layer), DVD-RW, DVD+RW; 24x CD

From http://www.apple.com/macbookpro/specs.html

These specs are for the current MBP, but I doubt there has been any significant change in quite a while. I remember 24x reads being available for the past several years.

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How does this translate into RPM? (i.e. - what is 1x in real, physical terms) –  bmike Aug 14 '11 at 23:34
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It depends on where on the disk you're reading. The outer edge of the disk has to spin faster to read at the same rate as the inner edge. So 1x is about 200-500 RPM (on the inside to the outside). There's a chart here: en.wikipedia.org/wiki/CD-ROM#Transfer_rates –  bahamat Aug 14 '11 at 23:50
    
That table boggles my mind. Does it really mean that if you record at between 1x and 12x the drive runs CLV - but at 20x it shifts to CAV? That would mean the data is physically recorded with different spacing and capacity base on the data rate? Could that mean some discs will never play in older drives when burned on a newer "high-speed" drive. (or do all drives now practically/effectively handle both CAV/CLV recording modes?) –  bmike Aug 15 '11 at 21:44
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