Timothy said:
Arno said:
In comp.sys.ibm.pc.hardware.storage PCR said:
Timothy Daniels wrote:
:
[.......]
An Extended Partition is
itself actually a non-bootable Primary Partition which is a
container for multiple Logical Partitions....
Perhaps "non-booting" would be a better term than
"non-bootable" because an OS within a logical drive inside an
Extended Partition
can be booted using the boot loader (e.g. ntldr for WinNT/2K/XP)
that can be in the Boot Sector of any one of the Primary
Partitions. IOW, in WinXP, one can have the MBR of the drive with
the highest boot priority (the "boot drive") pass control to the
Primary Partition marked "active" on that drive, and the boot.ini
boot menu in that active partition can point to an OS residing in
ANY partition - including a
logical drive within the Extended Partition - and boot load that
OS. I expect that the same flexibility exists for WinVista and
Win7. The restriction imposed on OSes residing on logical drives
within Extended Partitions is that their boot loader must be on
one of the Primary Partitions.
The implication of this is that an OS clone can reside
anywhere in the system - on any partition (Primary or Extended)
and on any enabled internal hard drive - and it can be booted to
running status without an intermediate "restoration" step needed
for OS "images". I believe this
also includes external eSATA hard drives if the motherboard has an
eSATA controller.
*TimDaniels*
I've found a more thorough explaination of what you've said...
http://thpc.info/dual/bootsequence.html
Boot Sequence in a Windows Dual-Boot Explained
It's a bit of a mind-twister, though, that the System partition
(marked Active in the MBR) contains the boot files
(NTLoader/IO.sys, etc.) &
the Boot partition contains the system files (Windows directory,
etc.). The System partition must be a Primary partition on the
primary controller. And the Boot partition can be anywhere, even
inside an extended
partition on a second hard drive. (It looks like even Win98 may be
able
to that using MSDOS! [which, actually, Chauvin may have brought up
here once long ago].)
Left out of that rather good discussion is the definition of the
"rdisk()" parameter in the boot.ini menu. It dodges the definition
by saying: "rdisk(0) is the first hard disk (rdisk(1) would be a
second disk)"
You are right. I was looking into rdisk() in another thread, & I wasn't
finding a site that fully explained it. I wanted its value to be...
0 - primary master
1 - primary slave
2 - secondary master
3 - secondary slave
And that probably still holds, except, with Blanton's help...
I'd say now rdisk(x) is derived from the order in which BIOS enumerates
the hard drives starting with the number 0, which normally is as shown
above. A slot that hasn't got a hard drive on it isn't counted. So, if
all the slots except the secondary master slot has a hard drive on it,
the secondary slave slot will need to have an rdisk value of 2 -- not 3!
In my ancient Dell PC, the Hard Drive Boot Priority is settable
in the
BIOS (a product of Phoenix Technologies), and it can arrange all 4
internal HDs in any sequence that you want, and the first HD in the
sequence corresponds to rdisk(0) (the 1st HD that the BIOS searches
to find an MBR), the 2nd HD in the sequence corresponds to rdisk(1)
(the 2nd HD that the BIOS searches to find an MBR), etc. Using that
nomenclature (called "ARC pathways") in boot.ini, one can designate
the location of the OS's partition as being partition(3) on rdisk(2),
for instance.
Ah. I see now what you meant by "the drive with the highest boot
priority (the 'boot drive')" above. It is the HDD that BIOS is set (for
those that can be set) to select to start the boot. So, to the thpc.info
site's...
BIOS > MBR (1st sector of disk) > OS Boot Sector Code of system
partition (Active) > boot files (system partition) > OS (boot partition)
...., you more fully explained BIOS's role. But, then, I should have
known that already, because I did know some BIOS can be set that way.
Also, the site did say the boot could start from a floppy too. But the
whole thing STILL is a mind twister to me!
Other BIOSs use less complete methods to set the HD Boot Priority,
some just "enabling" one HD as the drive containing the MBR and using
the physical data cable as the rdisk() location.
That sounds like my Compaq BIOS. It will only start its boot from the
Primary Master.
But the freedom to
put the OS's partition anywhere in the system (on any HD, in any
partition - including a virtual drive inside an Extended partition)
remains.
Nice enough. (But I'll bet I can do it with just Win98's MSDOS.sys too!
I'm starting to get irradiation burns from all these discussions of XP
stuff!)
I did consider Linux & even Apple overnight after my latest HDD crash
which had complications making it worse than the first. But I've fully
recovered!
In one of the microsoft.windows.* NGs, I believe, an old-timer
once described the legacy reason for calling the partition with the
loader the "System partition" and the partition with the Operating
System the "Boot partition". It made sense back in the DOS days,
apparently, when there was only one HD and the Boot and the
System partition were the same partition and had to be the first
partition on the HD. Correct me if I'm wrong, Roddy.
That still sounds like my own situation with a BIOS that boots from only
the Primary Master & with an MSDOS set for C:.
--
Thanks or Good Luck,
There may be humor in this post, and,
Naturally, you will not sue,
Should things get worse after this,
PCR
(e-mail address removed)
