Partition logic?

  • Thread starter Thread starter Ron Hardin
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Ron Hardin

If you create new partitions on the HD, what logic is used to
determine which ``belong'' to windows?

Do they get drive letters even if they belong to linux?

For that matter, why don't other partitions that come with XP
on dell, evidently swap and system restore, show up anywhere?

Do the partitions have names or something in the MBR to say what
to boot?
 
Ron Hardin said:
If you create new partitions on the HD, what logic is used to
determine which ``belong'' to windows?
Click to expand...

Nothing "belongs" to Windows. All Windows does is assume every partition it
recognizes (e.g., FAT, FAT32, NTFS, etc.) is something it should provide
access to, and through Disk Management, initialize and assign a drive
letter.
Do they get drive letters even if they belong to linux?
Click to expand...

A partition has an "identifier", a small field in the MBR for that partition
that tells the OS its type. If Windows doesn't recognize the type, it
ignores that partition, at most you will see "unknown" partition under Disk
Management, but no ability to assign a drive letter (btw, that's how boot
managers like BootIt NG, Boot Magic, XOSL, etc., HIDE partitions!).
For that matter, why don't other partitions that come with XP
on dell, evidently swap and system restore, show up anywhere?
Click to expand...

Because Dell has manipulated the indicator byte on the partition's entry in
the MBR such that the OS doesn't know what it is. When you use the recovery
CD, Dell's recovery system DOES, it copy the recovery partition in place of
your current partition, resets the partition indicator appropriately (e.g.,
FAT32, NTFS, whatever), and reboots. Whalla, you're in business again.
Do the partitions have names or something in the MBR to say what
to boot?
Click to expand...

The MBR can hold up to FOUR partition addresses. Besides the "type"
indicator, there's an active/inactive field as well for each partition.
When that's set to ON, that partition is recognized as the bootable
partition. When the BIOS loads the first sector from the HD (which is the
MBR), the MBR boot code looks for the first partition marked active and
boots that partition based on the address stored there.

HTH

Jim
 
Jim said:
The MBR can hold up to FOUR partition addresses. Besides the "type"
indicator, there's an active/inactive field as well for each partition.
When that's set to ON, that partition is recognized as the bootable
partition. When the BIOS loads the first sector from the HD (which is the
MBR), the MBR boot code looks for the first partition marked active and
boots that partition based on the address stored there.
Click to expand...

Can I have only 4 partitions then? or is there some indirect addressing
to get at others.
 
Ron Hardin said:
Can I have only 4 partitions then? or is there some indirect addressing
to get at others.
Click to expand...

Well, to be precise, you can have either 4 primaries, OR, 3 primaries and 1
extended. The extended partition can have one or more (essentially
unlimited) logical partitions. Usually logical partitions are used
exclusively as DATA partitions since they can not be *officially* booted due
to their indirect addressing (but like anything else, there's always an
exception, ppl have found ways to make the OS boot from the extended
partition, including me, but MS doesn't officially support it, so for this
discussion, let's assume it doesn't).

I almost hesitate to mention it, since it tends to open a can of words, but
just for informational purposes, I use BootIt NG, which does allow me to
have MORE than 4 primaries, indeed, as many primaries as I want. It's made
possible by the way the BootIt NG boot manager manages the MBR. It
dynamically builds the MBR before turning it over to the boot loader! So
you can define many, many partitions using BootIt NG, then define bootable
configurations that define which partitions you want to be loaded in the
MBR. When you select that configuration for booting, the BootIt NG boot
manager updates the MBR to reflect those configuration options, then passes
control to the boot loader. Unbelievably powerful and useful. But being
non-standard, you can't use other partitioning software to manage those
partitions (not that I need to, BootIt NG has its own partition manager and
imaging solution anyway, so the restriction isn't very important to me).

Anyway, just thought I'd throw that out there to make the issue even a
little more confusing, complicated :) As I said, when it comes to
computers, there always seems to be an exception to EVERY rule.

Jim
 
Jim said:
Well, to be precise, you can have either 4 primaries, OR, 3 primaries and 1
extended. The extended partition can have one or more (essentially
unlimited) logical partitions. Usually logical partitions are used
exclusively as DATA partitions since they can not be *officially* booted due
to their indirect addressing (but like anything else, there's always an
exception, ppl have found ways to make the OS boot from the extended
partition, including me, but MS doesn't officially support it, so for this
discussion, let's assume it doesn't).
Click to expand...

Great, finally (ha!) what is a swap partition? or swap area. Is it something
special that says to the OS use me for swap.

I mean I know what it's for but not how to create one or how it fits into
the scheme of partitions.

Of course thinking it would be nice if XP and linux used the same swap area.
 
Swap partitions are only for Unix/Linux style OSes. Windows XP does not use a
separate swap partition. It has a swap file.
 
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