Quote:
Originally Posted by BSDfan666
Sometimes this emulated device will have geometry that's different from what was determined via the umass/sd(4) probing, the side effect is the second stage loader cannot find /boot on some systems. (..you'll likely see "ERR M" if this is the case).
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As an anecdote, I have seen this when developing an application to clone disks on Sun hardware which expects all partitions to be aligned on cylinder boundaries. When attempting to use
dump(8) &
restore(8) on an identical disk which was attached via USB, I still had to massage where partitions were located such that they could later be mounted; a straight bit-by-bit copy
(even using dd(1)...) would lead to incorrect results because the
sd(4) interface exposes a different geometry than
wd(4).
FWIW, i386 & macppc platforms don't have this additional requirement. Copying from
wd(4) to
sd(4) works fine. Cylinder alignment is simply specific to Sun hardware done to improve performance.