Question About Primary Partitions...

E3000

Member
Aug 23, 2002
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Hey yo,
Is it possible to have two Primary Partitions on the same drive? I never thought so cos primary is primary and if there were two then it wouldnt be primary (or something), but i read in some MCSE book that it was possible to have two. Maybe this is just an NT/2000 thing... or what?

Also, does anyone know where i can find the FAQ on Dual Booting? I know how to do it (install two OS's, preferably on two different drives/partitions) but i want to know if there are any special things that i should know or better ways of doing stuff... or whatever...

If i have two 40gig drives and i split the first one (a) into 3parts (10/10/20), and i leave the whole of the second drive (b) as one big 40gig partition/drive... will the drive letters be assigned to:

C: (a-part1)
D: (b)
E: (a-part2)
F: (a-part3)

???
 

sep

Platinum Member
Aug 1, 2001
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Yes it's possible...with a third party software like partion magic. Every time I tried to do this with windows or dos it only allows one primary.

FAQ...try NTFAQ. If your only using Windows 9x and NT then it's easy. Just install the ealier version first ant NT over top. Make sure to have at least two partions. The OSs share certain files and will cause problems if ther both on the same drive (I did this before and could have use Outlook in Win98).

You can set the drives letters using NTs drive manager to change them. The order would depend on the partition order you created them...I think!

Good Luck!
-JC
 

SemperFi

Platinum Member
Apr 5, 2000
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2000 and xp can handle 2 primary partitions. I am not sure about nt4. None of win 9x will.

Semper Fi
 

Nothinman

Elite Member
Sep 14, 2001
30,672
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You can have up to 4 primary partitions on x86 boxes, it's a limitation of the BIOS. One of the partitions can be an extended partition which is just a container for any number of logical partitions so that you can get around the limit of 4.
 

NogginBoink

Diamond Member
Feb 17, 2002
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You can have up to 4 primary partitions, but only one of them should be marked Active. (Active = bootable. And while you're only supposed to mark 1 active, it's possible to mark more than one of them active, but behavior would probably be somewhat unpredictable.)

This is not a limitation of the BIOS, it's a limitation of the architecture of the master boot record. There's space in the MBR to define four partitions. If you define an extended partition, a pointer is stored in the MBR that points to a second "pseudo-MBR" at a location elsewhere on disk.

The partition table is stored in the first sector of the disk in a very well structured format. And there's only room for 4 entries there.

NT4, W2K, and XP will all allow you to define up to 4 primary partitions in the disk management interface in the product.
 

Nothinman

Elite Member
Sep 14, 2001
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(Active = bootable. And while you're only supposed to mark 1 active, it's possible to mark more than one of them active, but behavior would probably be somewhat unpredictable.)

The BIOS scans the partition table in order looking for the active partition, so it should pick the first one, although like you said there's no guarantees.

This is not a limitation of the BIOS, it's a limitation of the architecture of the master boot record. There's space in the MBR to define four partitions. If you define an extended partition, a pointer is stored in the MBR that points to a second "pseudo-MBR" at a location elsewhere on disk.

Technically it's both. On my Alpha instead of a x86 partition table I put a BSD disklabel on the disk which allows up to 8 partitions (partition c usually reserved for the entire disk), same thing on sparc and I believe everything else except maybe IA64 which IIRC has a different partition layout also.

Anyway, the only real issue is that Win9X may choke if there's more than 1 primary partition, all half decent OSes handle it just fine.