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Re: Darwin disk I/O question

Rob Braun wrote:

> On Thursday, Jan 2001 at 8:55:3 Dave Yost wrote:
>> I am seeking a disk driver expert who knows about the following:
...
>> ld there have to be a change to the driver protocol?
>
> After taking a recent EE course from a guy from Quantum, there is no
> such thing as CHS anymore from the disk's perspective. The disk really
> just makes those up and hands them to the OS/BIOS/Firmware as the normal
> interface to the disk. The disk really just takes these and maps them
> to it's internal structure that is almost always totally different.
> These days, the old CHS system is merely an interface to the disk that
> bears no resemblance to reality. One should not try to optimize
> disk requests on the assumption that these things match the physical
> layout of the disk. It is far better to just barrage the disk with
> requests and let it sort them out.

This seems to have been true for a while (ie since EIDE) - Tanenbaum's book
talks about it and its relationship to MINIX;

A. S. Tanenbaum and A. S. Woodhull, Operating Systems Design and
Implementation, 2 ed. Upper Sadle River, New Jersey: Prentice-Hall
International, Inc., 1997. pp 200-220

Steve.
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References: 
 >Re: Darwin disk I/O question (From: Rob Braun <email@hidden>)



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