Question What drive letters should not be used (because they are used by Windows) ?

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Kletoss

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What drive letters should not be used (because they are used by Win)?

After a new install of Win it uses / assigns special drive letters, e.g. C: for Win and, I believe, G: for DVD drives? Or is it H:? So these letters obviously should not be used for one's (external) hard drives, etc. Are there further letters which should not be used by the user (to avoid conflicts)?
 
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TerryLaze

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Kletoss said:
Sorry, I do not understand, that somehow sounds contradictory. Can I use A and B? Or should I not use them?
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A and B are traditionally used for floppy drives, for a long time before HDD became affordable most PCs only had A and B and where using them for floppies.
So that is also the reason that when hard drives became affordable they became the default C drive and then cd-rom came along to become the D drive.

None of those are any standard, just lose baselines most people (and Oses) follow.

you should not change any drive letter of a drive that already was assigned because then installed software will not know the new letter and will fail to work, other than that you can use any letter for any drive.
 
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CountMike

CountMike

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Kletoss said:
What drive letters should not be used (because they are used by Win)?

After a new install of Win it uses / assigns special drive letters, e.g. C: for Win and, I believe, G: for DVD drives? Or is it H:? So these letters obviously should not be used for one's (external) hard drives, etc. Are there further letters which should not be used by the user (to avoid conflicts)?
Click to expand...
Letters are not assigned to disks but partitions.
Only C: partition is reserved for Windows system files and even that can be circumvented by BOOT-ing from another disk and installing windows on another.
In typical Windows installation, windows will assign letters (other than C : to other partitions on same or another disk according to disk's position in connections to MB. If you move them to another possition letters may automatically change. That most usually happens to external drive.
 
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USAFRet

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A and B should, today, only be used for USB flash drives. If you must use them at all.

WIndows still treats those letters as 'floppies', and treats them a little differently.
For instance, no Indexing.

Any other letter after C...either let WIidows assign it or you give the drive a particular letter.
 
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Kletoss

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Thank you very much!

So then I would use all of the letters (besides of C:) and tried to avoid using D: and E: to automatically be assigned by Win. E.g for USB Sticks, SD Cards, etc. I guess, I have only two letters left to use, all the others already are in use. After a new Win installation I have to assign the letters of all of the hard drives again, that is annoying. And it is error prone when Win assigns wrong letters for these drives.
 
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Inthrutheoutdoor

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Phillip Corcoran said:
Windows is usually quite capable of assigning drive letters at boot time without any user input being necessary.
Click to expand...

^^THIS^^

So if you have a an optical drive connected that windows designates as "D" for example, then connect another fixed drive, windows will automatically assign another letter to it, probably "E".

Then if you connect an external HDD/SSD etc, windows will again auto-assign the next available letter that follows the ones already in use (in this case, "F"), unless you reformat the drive & assign a different one yourself, which you can easily do nottaproblemo.....

And FYI, this mechanism was worked out way back when the "plug & play" routines were being developed at the dawn of the multi-port, multi-input connector age, and really came into mainstream use when USB came along....
 
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Karadjgne

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A is the only unusable drive assignment. It's reserved permanently in Windows, not by Windows. B is reserved by Windows. Slight but significant difference as B can and often is used by Windows as Recovery partition. B can be User assigned and accessed, A cannot, normally. It's only use now is by Vendors like Lenovo or Dell etc to contain Vendor specific Recovery, like all the original bloatware and Factory default settings/data etc.

I have 1 physical drive in my pc, partitioned B, C. If I plug in a USB, it starts at G. My old pc had 2 physical drives B/C and E, USB started at G. Bootloader always started as K.

Windows doesn't care what the drive/partition letter assignment is, it can be anything but A, the letter assignment being totally unimportant as Windows uses every installed drive as a 'C' extention, unless it's storage added After installation, and therefore seperate. It's why you should never have drives other than the OS drive installed during Windows install as it sees any removal of any physical drive as taking away part of C, and then you get errors.
 
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USAFRet

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Karadjgne said:
A is the only unusable drive assignment. It's reserved permanently in Windows, not by Windows. B is reserved by Windows. Slight but significant difference as B can and often is used by Windows as Recovery partition. B can be User assigned and accessed, A cannot, normally. It's only use now is by Vendors like Lenovo or Dell etc to contain Vendor specific Recovery, like all the original bloatware and Factory default settings/data etc.
Click to expand...
You can assign A and B to drives or partitions.
Windows absolutely allows this.

Whether you should or not is a different question.
 
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hotaru.hino

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kerberos_20 said:
A and B letters are reserved for removeble drives, if you use it on internal drives, windows will still treat them as external
no indexing, no defragmentation, no system recovery backups and so on
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Windows doesn't treat drives as external based on drive letter. It doesn't care what you put as A: or B: and the only reason why it starts as C: is purely for backwards compatibility reasons. The only reservation Windows makes is assigning any floppy drive it sees as A/B first, again purely for backwards compatibility reasons.
 
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USAFRet

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www.howtogeek.com

What Are the Windows A: and B: Drives Used For?

The C: drive is the default installation location for Windows, if you have a CD/DVD drive on your machine it’s likely the D: drive, and any additional drives fall in line after that.
www.howtogeek.com www.howtogeek.com
"So largely the reason for starting the hard drive at C is for backwards compatibility. While the OS has abstracted data storage to some degree, it still treats A and B differently, in such a way that allows them to be removed from the system without altering the OS, caching them differently, and due to early viruses treating their boot sector with more caution than the hard drive’s boot sector. "
 
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kerberos_20

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hotaru.hino said:
Windows doesn't treat drives as external based on drive letter. It doesn't care what you put as A: or B: and the only reason why it starts as C: is purely for backwards compatibility reasons. The only reservation Windows makes is assigning any floppy drive it sees as A/B first, again purely for backwards compatibility reasons.
Click to expand...
it does, microsoft has documentation for it aswell...im too lazy to go through ms gibberish
but here you can check aswell, go to drive management, change drive letter to a and popup will appear
xoPv9Hp.png

choose what happens with removable drive...hmmm what do you think that is? autoplay on internal drive? maybe new feature?

btw if you get usb or internal floppy or tape drives, those gets auto assigned A and B letter
 
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Kletoss

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Very strange, A: and B: appear to be used here like any other letter, no problems so far.

Well, getting to running out of drive letters (23, not incl A B C) is rather unusual.
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Sorry, I still don't understand what the screenshot would be for, but anyway. Besides of that the drives are not running at the same time. And besides of that my Notebook didn't start this morning (blue screen). So I had to reinstall Win completely again and I still have to assign each letter again.

no indexing, no defragmentation, no system recovery backups and so on
Click to expand...
For internal drives and / or external ones?
 
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kerberos_20

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Kletoss said:
Sorry, I still don't understand what the screenshot would be for, but anyway. Besides of that the drives are not running at the same time. And besides of that my Notebook didn't start this morning (blue screen). So I had to reinstall Win completely again and I still have to assign each letter again.
Click to expand...
windows will give it any free letter, once you unplug drive, letter will become free for something else you plug in there

if those drives are external and you really must use some specific drive letter, than you can use autorun (autoplay) feature of external devices, in there you can launch change drive letter commmand so drive letter wont move
looks like i havent used it for a while...its gone for security reasons
 
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USAFRet

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Kletoss said:
Sorry, I still don't understand what the screenshot would be for, but anyway. Besides of that the drives are not running at the same time. And besides of that my Notebook didn't start this morning (blue screen). So I had to reinstall Win completely again and I still have to assign each letter again.
Click to expand...
You have 20+ physical drives attached to this system?
Or multiple partitions on some of these drives, each partition with their own drive letter?

I asked for the screencap, because in virtually every system whereby the user is nearing to run out of drive letters, it is the result of a really weird and really bad setup.


Also, drives and partitions can be mounted in Windows without a drive letter.



But, if this config works for you, have at it.
I have 6 physical drives in my system, and 6 drive letters.
Flash drives would get some other letter, but that is only temporary.
 
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