Windows 7 - What is maximum number of drives? Or maybe...

Asked By Tcs on 06-May-07 03:51 PM
I have just encountered a problem, which I didn't have before...

I've just upgraded from an old PC, running Windows 2k Pro (sp4), to a
new one running XP Pro (sp2).  (I have built both PCs, just as I have
always done.)  My configuration is:

Drv | OLD PC| NEW PC| # | description
A: | x     | x     | - | floppy
B: | -     | -     | - | doesn't exist
C: | x(10) | x(35) | 0 | OS partition (active)
D: | x (5) | x (8) | 0 | comm partition
E: | x (5) | x (8) | 0 | graphics partition
F: | x (5) | x (8) | 0 | word proc partition
G: | x (5) | x (8) | 0 | database partition
H: | x (5) | x (8) | 0 | various data
I: | x     | x     | - | CD / DVD-ROM drive
J: | x     | x     | - | DVD drive
K: | x     | x(10) | 1 | OS partition (active)
L: | x(320)| ????? | 2 | misc
M: |       | x (5) | 1 | comm partition
N: |       | x (5) | 1 | graphics partition
O: |       | x (5) | 1 | word proc partition
P: |       | x (5) | 1 | database partition
Q: |       | x (5) | 1 | various data
R: |       | x     | - | card read 1st drive
S: |       | x     | - | card read 2nd drive
T: |       | x     | - | card read 3rd drive
U: |       | x     | - | card read 4th drive
V: |       | x(160)| 3 | misc

Right now, disk 1 in the new PC is my disk 0 from my old PC, while I
continue to migrate from the old to the new.  *Normally*, I would only
have one, perhaps two partitions on disk 1.

Hard Disk 0 = 80gb
Hard Disk 1 = 40gb right now, but varies (win 2k hdd 0)
Hard Disk 2 = 320bg right now, but varies
Hard Disk 3 = 160gb right now, but varies

1.)  Disks 0, 1 & 2 are in removable cartridge/chassis.
2.)  Disk 3 is an external unit with USB interface.
3.)  All hard disks are IDE.
4.)  Disks 0, 1 & 2 are in the chassis.
5.)  Disks 0 & 1 run off the mobo's controllers.
6.)  Disk 2 runs off a SIIG Ultra ATA/133 PCI controller.
7.)  Drives R:, S:, T: & U: are card reader unit (Koutech F7210).

I can disable drives R:-U:, by "stopping" the USB device, although I
don't actually "remove" anything.  I was able to get my system to
then back to "on".  ( I don't believe it was the "scan for hardware
changes" that worked. )

So...I'm thinking this has to do with the number of physical "disks"
in the system.  ( So far I haven't been able to find anything about
what any such limit might be. )  But maybe it's a matter of the number
of "drives".  Maybe some combination.  Whatever it is, I would like to
know.  I'm also wondering if it would be possible to script the
disabling of drives R:-U: and enabling of drive L:.  And...if so, how
to do it.  Can I restrict the enabling of drives R: thru U: to perhaps
just ONE (1) drive?  ( I only have one Compact Flash card. )

Can anyone out there help me?  Any help would be appreciated.

Thanks in advance,


Shenan Stanley replied on 06-May-07 04:29 PM
I think you have gone into overkill on the number of partitions.
You do not *need* that many.

Most get along just fine with one (1) partition per drive.
Many get along better in that way and organizing their files/installations
into folders.

You have not ran out of drive letters - but you have a riduculous number of
I have systems with 2+TB of space on them and connectivity to several
external drives and network devices and seldom get over 12-15 drive letters.

Why not make an image of the old disk using somehting like Symantec Ghost,
Acronis TrueImage, BootItNG - and then read from the image to save your
machine from having to parse the abnormal number of tiny partitions? heh

Shenan Stanley
How To Ask Questions The Smart Way
Wesley Vogel replied on 06-May-07 06:53 PM

A computer can use up to 26 drive letters. Drive letters A and B are
reserved for floppy disk drives, but you can assign these letters to
removable drives if the computer does not have a floppy disk drive. Hard
disk drives in the computer receive letters C through Z, while mapped
network drives are assigned drive letters in reverse order (Z through B).
To assign, change, or remove a drive letter

Or paste the following line into Start | Run and click OK...

hh diskmgmt.chm::/dm_drive_letter.htm

Hope this helps.  Let us know.

MS-MVP Windows Shell/User

Tcs <> hunted and pecked:
Gerry replied on 08-May-07 06:04 PM

26 is not the max. You can have any number of C drives as long as the
operating system residing therein  cannot see any of the other C drives.



Stourport, England
Enquire, plan and execute
Wesley Vogel replied on 09-May-07 08:20 PM
Hi Gerry,

On one Windows operating system you can have as many drives as you like.
But you can only designate 26 of them with drive letters, from A thru Z.

Hope this helps.  Let us know.

MS-MVP Windows Shell/User

Gerry <> hunted and pecked:
PVS R replied to Wesley Vogel on 28-Sep-10 01:08 AM
Then how do we designate the rest ??
Brad B replied to PVS R on 31-Oct-10 01:52 PM
An explanation of one way to do it here:
Brad B replied to PVS R on 31-Oct-10 01:54 PM