We pretend we have one head with two megabyte worth of sectors per cylinder.
The code try to access another head in what it belives to the same
physical cylinder, because it belives that it would be faster than
waiting for the next free sector under this head to come around.
Most modern drives doesn't have a "classical" geometry, and thus
we end up fooling ourselves doing the above optimization. With this
change we will fill a cylinder sequentially if we can, and thus get
much more mileage from the track-buffer/cache built into the drives.
As a result a lot of seeks to the next or previous track should be
avoided by this.
(My disk is a lot less noisy actually...)
You can still get the old behaviour, by specifying zero for the
numbers.
This will also solve the problem with newfs barfing at really big
drives.
Obtained from: adult advice from Kirk.
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