[win2kforum] Re: Off Topic NT 4.0
- From: Matt Neimeyer <mneimeyer@xxxxxxxx>
- To: win2kforum@xxxxxxxxxxxxx
- Date: Wed, 09 May 2001 13:26:01 -0400
>Sorry to bring this up but I thought that NT was limited to a 4GB
>system/boot partition. Q224525 and Q114841 state that the boot partition
>must be entirely within the first 7.8 GB of the drive. Whenever I install
>NT 4.0 I am clearly limited to 4 GB. Did I miss something over the
>years????
It's been a while and lets see if I can remember the right terms but here's
why....
Those are two different issues... Both are artifacts of the so called "2gig
limit" and have to do with the computer getting to your data when it
represents the location of that data in a certain size integer (I believe
they both use 32bit integers). A simplistic example is this: How do you
count to 11 on your fingers? Once you get to 10 most people can't go any
higher... Some people I've seen count the bumps on their fingers. They
didn't count on their thumbs and three bumps per finger giving you 12 per
hand and 24 all together. (On pointer finger 1-2-3, on middle finger 4-5-6,
on ring finger 7-8-9, on pinkie 10-11-12, same on other hand)
If you remember in DOS (using FAT16) you could only create a partition that
was 2Gig. It gets a little more complicated than that... the 4 gig limit in
NT is part of that "more complicated". The limit for FAT16 is really X
clusters... or something like that... So if you have larger clusters you
can get beyond 2 gig and NT supports ridiculously large clusters which
allows 4gig. This is sort of like the finger thing where you still have the
same number of fingers but you change the way you count so you can get to a
higher number. The reason this affects NTFS partitions as well is that the
NT installer creates a FAT16 partition and then converts it to NTFS so you
are limited to 4 gig on the NTFS partition... you can get around that by
using something like Partition Magic to create your system partition as
NTFS to begin with.
That the partition must be within the first 7.8 gig of the drive is an
issue relating to the Boot Loader. Like the 2gig partition limit using
clusters and only being able to find things under a certain number of
clusters the BIOS can only find the operating system boot launch code
(NTLDR for NT... I think... and Command.Com for Dos and Win9x) if it's on a
part of the physical disk that is under a certain number of physical
"whatever" of the disk... If I remember correctly the magic number in this
case is the number of cylinders BUT it's probably more complicated. Suffice
to say the result is the same.
For this combination of reasons Microsoft recommends never creating a
system partition that is more than 7.8 gig and never higher than 7.8 gig on
the disk. This way no matter where in the partition your boot files end up
you can still get to them to boot. In theory no application (particularly
disk utilities like defragmenters) but the operating system should move
those files but it has happened to me.
Matt
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