Messages in this thread | | | From | (Linus Torvalds) | Subject | Re: disk head scheduling | Date | 20 Mar 1999 00:02:09 GMT |
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In article <19990319181823.A543@anjala.mit.edu>, Arvind Sankar <arvinds@mit.edu> wrote: > >IBM claims that my hard disk (Model IBM DHEA-38451) has 4 platters and 8 heads. >I assume these are physical, since there are either 15 or 16 logical heads in >CHS mode (settable via jumpers).
Do they claim how many sectors?
I bet they don't. A lot of the better disks split up the disk in "regions", and have a variable number of sectors: more sectors on the outer edge where there is more room, etc.
Density is important to modern disks, and as long as disks rotate you will have a property where the outer tracks have more space.
Quite frankly, anybody who even _thinks_ he knows how the disk is organized is living in the past. Give up on it, and just consider it a linear array of sectors. Anything else just amounts to repeatedly hitting yourself on the head with a virtual icepick, and is just about as useful.
Just say no to unnecessary complexity that just doesn't buy you anything. Linux uses a one-way scheduler for many good reasons, not the least of which are that it is fair and that it is simple.
The same goes for filesystems: trying to optimize the filesystem for some random number of sectors per track is just stupid these days.
Linus
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