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Difficulty Assigning Drive Letters



 
 
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  #1  
Old November 3rd 20, 02:34 PM posted to alt.comp.hardware.pc-homebuilt
John B. Smith
external usenet poster
 
Posts: 163
Default Difficulty Assigning Drive Letters

Last weekend I installed a new boot drive after months of intermittent
problems. I used Macrium Reflect to image my two booting partitions
onto the new drive. I was anticipating a huge fight but it went
amazingly well. I bought a larger drive this time 1T. About half of it
was left after I partitioned for the XP and Win7. With both booting
successfully I decided to use the remainder of the drive for data
partitions. I made two equal size partitions, using Win7 Disk
Management. The first one insisted on being a Primary partition, I
couldn't find a way to make it anything else??? I wanted to use drive
letters that followed the letters on my other data drive, so 'N' and
'O'. When I booted XP I went to its Disk Management. XP had decided to
call them 'E' and 'F'. The second partition, which Win7 had deigned to
desigate a logical drive, renamed no problem to 'O'. But the primary
partition that Win7 had made drove XP Disk Management into lala land
when I tried to rename it, and it took forever for XP to close down
after my attempt.
So.... I guess I want to make two logical drives, instead of one that
is a primary, in order to name them the same letter in both OS's.
Or a way to defeat XP's naming hangup? I kind of thought I wanted to
do my partitioning in Win7, to keep the boundaries right (or
something). Anybody have ideas about the best way to approach this?
  #2  
Old November 3rd 20, 04:38 PM posted to alt.comp.hardware.pc-homebuilt
Paul[_28_]
external usenet poster
 
Posts: 1,467
Default Difficulty Assigning Drive Letters

John B. Smith wrote:
Last weekend I installed a new boot drive after months of intermittent
problems. I used Macrium Reflect to image my two booting partitions
onto the new drive. I was anticipating a huge fight but it went
amazingly well. I bought a larger drive this time 1T. About half of it
was left after I partitioned for the XP and Win7. With both booting
successfully I decided to use the remainder of the drive for data
partitions. I made two equal size partitions, using Win7 Disk
Management. The first one insisted on being a Primary partition, I
couldn't find a way to make it anything else??? I wanted to use drive
letters that followed the letters on my other data drive, so 'N' and
'O'. When I booted XP I went to its Disk Management. XP had decided to
call them 'E' and 'F'. The second partition, which Win7 had deigned to
desigate a logical drive, renamed no problem to 'O'. But the primary
partition that Win7 had made drove XP Disk Management into lala land
when I tried to rename it, and it took forever for XP to close down
after my attempt.
So.... I guess I want to make two logical drives, instead of one that
is a primary, in order to name them the same letter in both OS's.
Or a way to defeat XP's naming hangup? I kind of thought I wanted to
do my partitioning in Win7, to keep the boundaries right (or
something). Anybody have ideas about the best way to approach this?


The lettering is stored in the Registry, as far as I know.

There should not be a problem having multiple OSes, and each OS
having a different "letter map".

This is in part, because when a particular OS boots, its partition
becomes C: , and if some other letter was assigned in another OS time
interval, and there wasn't flexibility, then you would be playing
whack-a-mole worse than you are at present. Nobody wants to boot
an OS, and discover the OS drive is F: or something. There are ways
to finagle things to make that happen, but it doesn't happen
without setting a trap for the OS.

Drive lettering only becomes a problem for third party utilities,
such as Kaspersky Rescue Disc. It presents a menu of drives to
scan, and the menu has to be made from "some" map. If you had
WinXP and Win7, it would select one of the OSes as "boss of the definition"
and use the drive lettering it contains. Proof of which one, would
exist in the form of figuring out which drives pagefile.sys is being
used as a temporary Linux swap for the Linux OS on the Rescue CD.
That's an example of when somebody has to make a choice as
to what to do. Windows users are not normally forced to
make a decision as to "which Registry runs things".

Part of the information is in the Mountvol key.

In WinXP, in Command Prompt, you can type

mountvol

And stuff like this is printed on the screen.

*******
Creates, deletes, or lists a volume mount point.

MOUNTVOL [drive:]path VolumeName
MOUNTVOL [drive:]path /D
MOUNTVOL [drive:]path /L

path Specifies the existing NTFS directory where the mount
point will reside.
VolumeName Specifies the volume name that is the target of the mount
point.
/D Removes the volume mount point from the specified directory.
/L Lists the mounted volume name for the specified directory.

Possible values for VolumeName along with current mount points a

\\?\Volume{50acaf00-3981-11e6-97f4-806d6172696f}\
E:\

\\?\Volume{50acaf01-3981-11e6-97f4-806d6172696f}\
F:\
*******

Those two drive letters are next to one another, on the
same disk. The first chunk, you can see a single digit
changing, to separate the values used.

That's not particularly important, but it's to show that
each OS is keeping some sort of record. I would hope
(but have not verified) that the string is the same in
every OS, but the letter assignment can change.

To assign a letter, you'd likely need an account belonging
to the administrator group. It's possible a Guest account
would not have permission to assign a new drive letter.

You can assign a letter, even to a RAW volume. A RAW volume
has a partition type, like 0x07 NTFS, but the first sector
is missing a file system header. For example, when formatted
NTFS, the first sector of an NTFS volume has the string "NTFS"
part way down the sector. I use that occasionally as verifying
"I might be on target". Unfortunately, you'll find similar
looking sectors all over the place, so it's easy to get fooled
doing that. I'm only using that when using dead reckoning
math. If you can set a drive letter on a RAW volume, that
tells you the drive letter is not stored inside the actual
volume.

To look around a raw disk, HxD has a menu for opening a disk
drive read-only. The menu is functional if the program is
started using 'Run As Administrator' on Windows 7. It has to be
elevated, as does using "dd.exe" or PTEDIT32.exe .

https://mh-nexus.de/en/hxd/

Anyway, there's not much point of heading in this direction,
because it's not solving your lettering problem. There can
be conflicts between mapped drives and USB keys that have
just been inserted. I don't know if that is somehow
involved in your conundrum. Uwe Sieber's "USBDLM" drive letter
manager program, can be used to better manage automatic letter
assignment under those conditions (using mapped drives a lot).

There is also

subst /?

which allows assigning a drive letter to a path. This
allows "making a volume from a tree on some partition".
It would typically be used as a way to shorten a path
name, to stay within the roughly 260 character limit,
and might be used if access was otherwise denied. It's
from the MSDOS era, and I don't know how it stores its
letter assignments. Since the letter would not show up
in Disk Management, there might be no way to track it...
other than learning how it is stored in the Registry.
As SUBST would need to store the details somewhere in
the registry.

I doubt "mountvol" will provide any useful intelligence,
as far as solving the "lalaland" problem. But something
is interfering with the letter process. I can't be sure
just what that is.

Paul
  #3  
Old November 3rd 20, 08:04 PM posted to alt.comp.hardware.pc-homebuilt
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default Difficulty Assigning Drive Letters

"John B. Smith" wrote:

I made two equal size partitions, using Win7 Disk Management. The
first one insisted on being a Primary partition, I couldn't find a
way to make it anything else???


There must be a primary partition, so it can be marked as the active one
in the partition table. The BIOS/UEFI finds an active-marked partition
in the order it searches the drives to find the boot sector for the OS
in that partition. The BIOS bootstraps itself, finds the boot sector,
loads that into memory, and passes control to it. You cannot mark a
logical partition as active, because it is under a parent partition.
Even if the parent were marked as active, the BIOS wouldn't know which
of its children (logical partitions) was the one to use for booting.

That's a limitation of the standard bootstrap program in BIOS. Other
multi-boot managers can load the boot loader in any partition on any
drive, and even give you a menu of which to choose (and some don't
require they even be within a partition nor any part of an OS in a
partition, so they load before any OS loads; i.e., you're trying to use,
for example, Windows boot manager - load Windows boot loader, load its
dual-boot manager, select an OS elsewhere, and load that boot loader.

The max is 4 partitions per drive, because the MBR (Master Boot Record)
has only 4 entries in its partition table. One of those entries can be
for an extended partition, but logical partitions don't really exist.
They are defined as portions or zones of the extended partition. You
cannot mark active an extended partition, but that won't say which of
the logical partition for where to find an OS boot loader.

Newer computers use UEFI (Unified Extensible Firmware Interface) instead
of the old BIOS+MBR scheme (although UEFI keeps a copy of the MBR in a
portion of the UEFI data). The whole UEFI scheme is more complicated;
see:

https://docs.microsoft.com/en-us/win...ive-partitions
https://www.howtogeek.com/56958/htg-...lace-the-bios/

According to https://en.wikipedia.org/wiki/GUID_Partition_Table, looks
like there could be up to 128 partitions per drive defined in LBA 2-33
in the GUID Partition Table. Yikes! Tis probably the reason, along
with switching long ago to LBA (logical block addressing) allowing for
larger drives, why logical partition blocks defined under an extended
partition faded away. Even if still using the old BIOS/MBR scheme, I
never found a need to have more than 4 partitions on a drive, so they
could all be primary partitions.

Linux folks have their grub multi-boot manager. I haven't used it to
know if it occupies a partition with an OS, it's own partition, or can
use the first unassignable cylinder on the disk to store its code.
EasyBCD is another that I've heard about, but don't know where it stores
itself. I've used GAG (Graphical Boot Manager) a *long* time ago.

No matter which multi-boot manager you use, the BIOS loads first, and it
has to find where is the boot loader or manager that it has to load, and
it does that by searching the drives in the order found by looking in
the first cylinder of the active-marked primary partition for the boot
sector. There must be a minimum of 1 primary partition. With BIOS, you
could have up to 4 primary partitions, or a combination of 1 primary
partition and 3 other partitions (because there are only 4 partition
records in the partition table in the MBR on the drive). If you define
an extended partition (which cannot be active-marked) then you can
create logical partitions under it to give more than 4 volumes on the
drive usable by the OS.

I wanted to use drive letters that followed the letters on my other
data drive, so 'N' and 'O'. When I booted XP I went to its Disk
Management. XP had decided to call them 'E' and 'F'. The second
partition, which Win7 had deigned to desigate a logical drive,
renamed no problem to 'O'. But the primary partition that Win7 had
made drove XP Disk Management into lala land when I tried to rename
it, and it took forever for XP to close down after my attempt. So....
I guess I want to make two logical drives, instead of one that is a
primary, in order to name them the same letter in both OS's. Or a way
to defeat XP's naming hangup? I kind of thought I wanted to do my
partitioning in Win7, to keep the boundaries right (or something).


When in Disk Management, right-click on a volume (usually a partition)
and select "Change drive letter".

To eliminate the logical partitions (under an extended partition) and
convert them to primary partitions (max of 4 per drive with BIOS/MBR),
it's probably easier to use a 3rd party partition manager to do that.

The MBR has its partition table, and that is where the partition
definitions are stored, not inside any OS. Drive lettering is on a
per-OS basis, because those drive letter assignments are stored in the
Windows registry. Different operating systems can assign different
drive letters to the same partitions across multiple drives. On the
other hand, Linux doesn't use drive letters hence no limitation of 26
drive letters (A to Z) for volumes as there is for Windows.

In the Windows registry, drive letter assignments are stored at:

HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices

Each instance of Windows has its own registry hence why the same
partitions can have different drive letter assignments under separate
instances of Windows. That's why no drive has any drive letter
assignment until Windows loads. Before Windows loads, drives have to be
discovered or enumerated by their physical addressing. If your computer
uses the old BIOS/MBR scheme, you can run "bootcfg /list" (which reads
the boot.ini file) to see the physical addressing for the partitions,
which look something like:

multi(0)disk(0)rdisk(0)partition(1)\Windows

Disks are enumerated starting at zero (e.g., drive 1 is disk 0) while
partitions on a disk start with 1. For more information on boot.ini
definitions, see:

https://www.computerhope.com/issues/ch000492.htm

If using UEFI, boot.ini is not used, and bootcfg will complain that
boot.ini was not found.

If you want different drive letter assignments for the same partitions
in different instances of Windows, just load Windows and do the drive
letter assignments during that Windows session to save those drive
letter assignments into the registry of that instance of Windows. Don't
use Disk Management in Windows XP in trying to get the same drive letter
assignment in Windows 7, and visa versa. The drive letter assignments
are separately defined within each OS.
  #4  
Old November 4th 20, 03:22 AM posted to alt.comp.hardware.pc-homebuilt
Flasherly[_2_]
external usenet poster
 
Posts: 2,407
Default Difficulty Assigning Drive Letters

On Tue, 03 Nov 2020 08:34:48 -0500, John B. Smith
wrote:

Last weekend I installed a new boot drive after months of intermittent
problems. I used Macrium Reflect to image my two booting partitions
onto the new drive. I was anticipating a huge fight but it went
amazingly well. I bought a larger drive this time 1T. About half of it
was left after I partitioned for the XP and Win7. With both booting
successfully I decided to use the remainder of the drive for data
partitions. I made two equal size partitions, using Win7 Disk
Management. The first one insisted on being a Primary partition, I
couldn't find a way to make it anything else??? I wanted to use drive
letters that followed the letters on my other data drive, so 'N' and
'O'. When I booted XP I went to its Disk Management. XP had decided to
call them 'E' and 'F'. The second partition, which Win7 had deigned to
desigate a logical drive, renamed no problem to 'O'. But the primary
partition that Win7 had made drove XP Disk Management into lala land
when I tried to rename it, and it took forever for XP to close down
after my attempt.
So.... I guess I want to make two logical drives, instead of one that
is a primary, in order to name them the same letter in both OS's.
Or a way to defeat XP's naming hangup? I kind of thought I wanted to
do my partitioning in Win7, to keep the boundaries right (or
something). Anybody have ideas about the best way to approach this?


That is a clear reason why there are many aftermarket partitioning
software utilities, not to exclude GPartEd for *NIX flavors and
distributions. With the latter it may be possible to work with
advanced format volumes, such as exFat, not supported in all XP
iterations, not entirely, at all, prior to Windows 7 when linking
Windows 7 variously to some Android schemes and their firmware
implementation for Microsoft linkage-level and subsequent licensing,
if any, to how storage within such a device is apportioned (Fat32, for
instance, requires a royalty fee, Microsoft collects, for usage when
Microsoft owns its patented copyright.)

Perhaps that is generally why aftermarket partitioning software
utilities for the most would cost money to use, whether in some
instances indirectly provided by hard drive manufacturers under for
proviso of downloading upon proof of purchase of qualifying drive.

Much the same if in the case of Macrium Reflect, then among other
so-called "cloning operations", in some way Microsoft may less
intuitively provide, that advantage is then perceived over available
alternatives, whether at addition costs taxed or not.

To an extent of drive lettering, at least for aftermarket partitioning
software, that is by intent simplest to assess, much as provisioning
for further volumes within logical partitions from primary partitions
and how they differ;- the changes of drive assignment will then of
course remain consistent until the next Macrium Reflect restoration,
whereupon they will have to be reinstated but not rebuilt. Boot
Arbitrators may also further affect similar contingencies, insofar to
change drives for being hidden, or accessibly revealed, to a given OS
they're defined for, by the arbitrator during its configuration;- And,
again, as there are several arbitrator classes, each will
characteristically need further evaluation for specifications its
designed.

Basically, then there's three operative -- a) the restoration utility,
which well may account partitioning for subsequent adjustment to a OS
binary-streamed sector rewrite, b) partitioning utilities for
manipulating drive creation and space usages, and c) an arbitrator to
assign to the BIOS pointer: Sequential Ordering for Drive/Device
Identity to Access;- another mention would be within certain
possibilities is to have multiple Arbitrators inlaid into multiple
physical boot devices, not to exclude such as memory "USB
FlashSticks", all of which can be contained for unique instances to
preclude, or include, a structure of partitions from one another.

Beyond which, is yet another dimension to the Developers Platform,
wherein the platform, per se, is a software contingent to multiple
operating systems implemented at a support level (sic) designed to be
apart from foregoing limitations of each operating system, per
partition, solely and for occurrence at singularity. Android, UNIX,
Microsoft, would be less the obvious constraint to think of a project
name released in three program and OS versions, than, on the other
hand, a certain to "in-house" customization efforts, no doubt
exemplary to such among an obtusity for applications, say to
interstate utilities, over a matter of volatile oversight and
standards for monitoring energy telemetry distribution channels over
both private resources and a WEB infrastructure linkage.
 




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