WD1007V + big Maxtor + DOS + UNIX

[Tim Wright]

In <15900 at bfmny0.BFM.COM> tneff at bfmny0.BFM.COM (Tom Neff) writes:

...
>   disk this meant cylinders 85-1631.  Do it by specifying actual
>   cylinders rather than percentage of disk.

> * IGNORE what fdisk() then tells you!!  Some genius decided to do 10-bit 
>   modulo on all the cylinder numbers regardless of what the on-disk 
>   table *actually* contains, so it looks like it's telling you that
>   instead of creating your new 1540-cylinder partition you only created
>   a 576 cylinder one, only used 20% of the disk, etc, etc.  WRONG-O,
>   you did actually did do what you wanted, fdisk is just too dumb to
>   report its own results properly.  Press on...

Not true. The problem doesn't lie with fdisk, the problem lies with IBM
who in their infinite wisdom decided that you'd never have disk with >1024
cylinders on a PC (to be fair I suspect the old HD controller on a XT
couldn't support this, though I don't know for certain !). The BIOS can't
cope with >1024 cylinders (at least if you claim IBM-PC compatability !).
The modulo-2^10 is necessary and *IS* what is stored in the *fdisk* partitions
table which is not the same as the VTOC in the UNIX partition. This is *the*
reason for all this translation crap. You wouldn't need to translate except
to get around the brain-damage in certain so-called Operating Systems. The
upshot is that all bootable partitions must start before cylinder 1024,
otherwise you cannot make them bootable ! With this proviso in hand, UNIX
doesn't care where it is since the VTOC at the beginning of the UNIX partition
specifies all the unix partitions (within the relevant fdisk partition), and
the numbers here are not subject to stupid limits :-)

Hope this makes things clear,

Tim
--
Tim Wright, Dell Computer Corp. (UK) | Email address
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"What's the problem? You've got an IQ of six thousand, haven't you?"