Hard Disk requalification

  • Thread starter Thread starter Ian East
  • Start date Start date
William said:
There will be a great difference between accessing sectors in the "best"
order where a sector transfer is started just as it comes under the
heads, and the "worst" order, where a transfer is started for the sector
just passed. In the latter case, you will have to wait for a whole
revolution of the disk on every sector. The former case will operate as
fast as the physical disk will permit.
Click to expand...

See my comment on "interleave" below.
To make this happen, the program must know a lot about the physical
layout of the disk. That is largely hidden these days, but some clever
disk guys know how to do it.
Click to expand...

I agree, and Steve Gibson is one of the best "clever disk guys" around.
The problem is to access a sector in a way which stresses it using only
those commands which can be done through the IDE electronics on the
disk. Part of SpinRite "fools" the drive in ways which are not optimum
for speed. Steve explains some of this on his site.

I have no connection with GRC, but have used SpinRite since the early
days of "step motor track selection" hard drives. The original use of
SpinRite was to set the optimum sector interleave, which one could
select during a true low-level format.
 
There will be a great difference between accessing sectors in the "best"
order where a sector transfer is started just as it comes under the
heads, and the "worst" order, where a transfer is started for the sector
just passed. In the latter case, you will have to wait for a whole
revolution of the disk on every sector. The former case will operate as
fast as the physical disk will permit.

To make this happen, the program must know a lot about the physical
layout of the disk. That is largely hidden these days, but some clever
disk guys know how to do it.
Click to expand...


I've not read the Spinrite docs in a long time but what I
vaguely recall what that it is quite intentional to access
the medium in different, multiple directional strategies so
that differences in arm movement can also be (supposedly)
tested... or at least their impact on reading. Or maybe I
have that all wrong, it HAS been awhile since I read it, for
all I know it might've only applied to recovering data off
of floppies with spinrite.
 
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