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

[Kletoss]

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)?

 

[Kletoss]

windows will give it any free letter, once you unplug drive, letter will become free for something else you plug in there

Yes, that is the drawback, one cannot assign a drive letter that lasts over installations.

You have 20+ physical drives attached to this system?
Or multiple partitions on some of these drives, each partition with their own drive letter?

At the moment I have three partitions on the internal SSD, C:, J:, Y:. The other letters are for hard drives without partitions.

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.

How could it be done better?

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

Yes, I have read about that but I absolutely do not understand what the advantages are, if I could use it usefully. Does one have to mount the drives and partitions on a new installation again?

But, if this config works for you, have at it.

Well, I just plug a drive in when I want data from it or do anything on it and plug it off after. Not very convenient but apparently the cheapest way to handle something like that.

Flash drives would get some other letter, but that is only temporary.

So as Win assigns them.

 

[hotaru.hino]

As much as I would've want to let this go, I decided "eh, I should just do this anyway"

Does Windows treat A or B drive differently if it's a hard drive, specifically an internal one connected via SATA? The answer: no.

Here's a drive that has an A: drive letter assigned to it. As you can see it's using a SATA interface.

But does Windows disable write caching because it's supposed to treat it as "removable"? No. I'd show but it'd be discounted as "but you just clicked on it and screenshot it!" So moving on...

But Windows doesn't have indexing enabled for it! Windows doesn't have indexing enabled for anything other than your user folder and start menu by default.

But what about being able to back things up from it? Yes you can (EDIT: On another glance with a USB drive, it lets you back it up anyway.)

But when I assign it drive letter A:, autoplay pops up! It pops up whenever you switch drive letters for a partition anyway. Oh, and by the way, if SATA is running in AHCI mode, it's hot swappable. This autoplay showed up when I plugged in my drive while the OS was still running.

Also yes, you can disconnect the drive (data cable first, then power) and it'll just go away like any other removable drive.

So no, Windows does not treat A: (and presumably B: ) as anything different. It knows what the heck is connected to it.

 

[CountMike]

It's nearly impossible to run out of letters in windows. After A to Z it would start with AA, BB etc.

 

[SkyNetRising]

It's nearly impossible to run out of letters in windows. After A to Z it would start with AA, BB etc.

Not in windows.
You're confusing this with Linux and how drives are named there.

 

[Kletoss]

Does this apply to all external hard drives? Why the cable first?

Does this apply to all external hard drives? Why the cable first?

 

[USAFRet]

So as Win assigns them.

So if these drives are not always connected, how are you almost running out of drive letters?

"running out" would imply that they are connected all the time.

 

[USAFRet]

How could it be done better?

Well, we had a guy here a while ago, wanting to know how to alleviate the "no more drive letters "problem.
Wanted to implement AA, BB, etc.

Seeing his Disk management window highlighted the problem....simple disorganization.

On one physical drive, 3 partitions of:
H - Music1
J - Music2
K - Music3

Why were those simply not 3 folders on that 500GB drive?

Other physical drives were as bad or worse.

 

[Kletoss]

So if these drives are not always connected, how are you almost running out of drive letters?

Each drive gets a drive letter. When there are more drives (e.g. 30) than drive ltters (e.g. 23 ) there is no letter left to use. Not letter left to be assigned to a hard drive. So it is not possible to use a further letter.

"running out" would imply that they are connected all the time.

Why?

Why were those simply not 3 folders on that 500GB drive?

Yes. May be he had a usefully reason for this.

 

[USAFRet]

Yes. May be he had a usefully reason for this.

No, he did not. He just thought it had to be that way.

Each drive gets a drive letter. When there are more drives (e.g. 30) than drive ltters (e.g. 23 ) there is no letter left to use. Not letter left to be assigned to a hard drive. So it is not possible to use a further letter.

If a physical drive is not connected, it does not have a drive letter.

If you connect a new drive, and Windows needs a drive letter that used to be some other physical drive...it will just do it.

 

[TerryLaze]

Why?

Shut up and eat your dinner!
Oh no wait, because each time you disconnect a drive the drive letter becomes available again so any other drive you connect can get that letter.

I have a dozen or so sd cards/external hdds and they all show up as E: if I only have one at a time connected.

 

[DSzymborski]

Each drive gets a drive letter. When there are more drives (e.g. 30) than drive ltters (e.g. 23 ) there is no letter left to use. Not letter left to be assigned to a hard drive. So it is not possible to use a further letter.

This is why people keep desperately asking for details and context, because you have a highly unusual storage scheme, which, to anyone with a lot of experience, is going to sound inefficient at best or completely off the rocker at worst.

Sure, you have the right to not provide details. You also have the right to not have your vitals checked at a doctor's appointment, but then you can't be surprised if the doctor expresses confusion and then either gives you incomplete advice, missing key information, or simply outright refuses to diagnose you under these conditions.

 

[Kletoss]

No, he did not. He just thought it had to be that way.

OK, well, maybe it could have been interesting to know why he thought that.

If a physical drive is not connected, it does not have a drive letter.

Actually - although I have no idea - I would not think that, it has that one I assigned it to (and have written on a label on the drive) stored in the Win drive management.

If you connect a new drive, and Windows needs a drive letter that used to be some other physical drive...it will just do it.

Even if all letters already are assigned?

Shut up and eat your dinner!

Sorry, not hungry.

Oh no wait, because each time you disconnect a drive the drive letter becomes available again so any other drive you connect can get that letter.

Actually I would not think so. Assigned letters are reserved for special drives.

I have a dozen or so sd cards/external hdds and they all show up as E: if I only have one at a time connected.

Yes, the same here. As long as one does not assign them, I guess.

 

[USAFRet]

Actually - although I have no idea - I would not think that, it has that one I assigned it to (and have written on a label on the drive) stored in the Win drive management.

No.

It does not reserve that drive letter to the exclusion of never being able to use it on a different physical drive.

 

[hotaru.hino]

After messing around with drive letters and whatnot with Windows, this is what I can glean is the behavior with drive letters.

• Window doesn't assign "drive" letters to actual storage drives. It assigns them to partitions.
  • Certain devices like floppy drives and optical drives appear to have a letter assigned to the whole drive, but they're limited to having one partition anyway
  • If you notice, this doesn't apply to all drives with removable media. SD card readers tend to not show up in Explorer until you insert an SD Card. And yes, you can partition SD cards if you want.
• Particular letters do not influence Windows' behavior about that partition, as I noted previously.
• Windows assigns the next available letter to partitions that show up starting from C:
  • Windows starts at C:\ so as to reserve A:\ and B:\ for floppy drives for backwards compatibility reasons. But as mentioned, there's nothing stopping you from assigning A: or B: to any drive. If you insert a floppy drive after the fact, Windows will just move it on to the next letter.
• Windows "remembers" which partitions were assigned to which letter in the Registry at the location Computer\HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices. There's some identifier that the partition has (each partition has a unique ID, but it's not using that for some reason) and Windows uses that to "remember" which letter was assigned to it.
  • I say "remembers" because this only really works for storage that's attached at the time of boot or if you assign a drive letter that's towards the end of the alphabet.
  • So if you assign a partition F:, then remove it, then add more partitions such that the next available letter is F:, that partition becomes the new F: when it gets mounted.
• If Windows runs out of letters to assign partitions to, you have to start using mount points (https://superuser.com/questions/536886/what-happens-when-windows-runs-out-of-drive-letters). There are some ways to get around this, but they're either not supported or things will break in weird ways.
  • You can mount a partition to a folder even if it doesn't have a letter assigned to it.
  • You can do this with removable drives. If you take it out, when you put it back in, it'll be mounted to the same path assuming it exists. If you delete the path, the partition will need to be re-mounted.

 

[Kletoss]

It does not reserve that drive letter to the exclusion of never being able to use it on a different physical drive.

Very strange, here it is and was like that. I e.g. assign in a drive manager program a letter to a drive and it is ALWAYS assigned (automatically) in the same Win installation.

Many thanks for finding out.

Windows "remembers" which partitions were assigned to which letter in the Registry at the location Computer\HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices. There's some identifier that the partition has (each partition has a unique ID, but it's not using that for some reason) and Windows uses that to "remember" which letter was assigned to it.

If one had assignend the letter to a drive. It does not remember a drive being automatically assignend by Win, I guess.

So if you assign a partition F:, then remove it, then add more partitions such that the next available letter is F:, that partition becomes the new F: when it gets mounted.

It does not seem to be like that here.

Thank you for the link.

 

[hotaru.hino]

Very strange, here it is and was like that. I e.g. assign in a drive manager program a letter to a drive and it is ALWAYS assigned (automatically) in the same Win installation.

Many thanks for finding out.

If one had assignend the letter to a drive. It does not remember a drive being automatically assignend by Win, I guess.

It does not seem to be like that here.

Thank you for the link.

Drive letters aren't strictly reserved. Windows will remember to them to the extent that I described above. The only thing I believe is more or less permanent is mounting the partition to a folder and removing the letter association. As long as the path exists, the partition will be mounted there.

 

[Kletoss]

The only thing I believe is more or less permanent is mounting the partition to a folder and removing the letter association. As long as the path exists, the partition will be mounted there.

I do not understand what the advantage of mounting to a folder is (besides of not needing a new letter). Is it all the same like using a normal partiion? Is there a drawback doing that? So what is the difference between using a a mounted partition and using a common drive / partition?

 

[hotaru.hino]

I do not understand what the advantage of mounting to a folder is (besides of not needing a new letter). Is it all the same like using a normal partiion? Is there a drawback doing that? So what is the difference between using a a mounted partition and using a common drive / partition?

Yes, it's the same as using a normal partition. Going into the folder's Properties shows the same things as doing it the typical way.

The only difference is where the so-called mount point of the partition is. Partitions are normally mounted in a way that the root directory is accessed via a letter. Using a mount folder is basically the same thing as mounting other partitions/volumes/whatever in Linux.

 

[Kletoss]

That referes to Win also (or were we talking something about Linux the whole time?), I assume. Not only on Linux. I am on Win.

So using mount folders does not have any dranwback. Not even when trying to recover files (if there is a software / hardware problem)?

 

[hotaru.hino]

That referes to Win also (or were we talking something about Linux the whole time?), I assume. Not only on Linux. I am on Win.

So using mount folders does not have any dranwback. Not even when trying to recover files (if there is a software / hardware problem)?

The reference to Linux was to provide a similar example of how another OS does something.

Again, all a mount folder does is create a mount point for the root directory. Windows does not treat the partition definitely beyond that. So any operations on the partition the mount folder is in does not affect the mount folder. So things like defrag/optimization, indexing, etc. do not apply to the mount folder if you marked the partition it's on for those operations.

 

[Kletoss]

The reference to Linux was to provide a similar example of how another OS does something.

Sorry, I do not understand, it does not work that way on Win?

Again, all a mount folder does is create a mount point for the root directory. Windows does not treat the partition definitely beyond that. So any operations on the partition the mount folder is in does not affect the mount folder. So things like defrag/optimization, indexing, etc. do not apply to the mount folder if you marked the partition it's on for those operations.

So always only the partition / drive is effected then. Like it is on a partition / drive usually used.

 

[hotaru.hino]

Sorry, I do not understand, it does not work that way on Win?

By default no. In Linux the OS partition is mounted as the root directory and every storage device after that has to mount on a folder. By default, Windows mounts partitions are mounted with letters, but there's the option of mounting them on folders, like Linux.

So always only the partition / drive is effected then. Like it is on a partition / drive usually used.

Yes.

 

[Kletoss]

So what for can you use mounted folders at all, when does it make sense to use them? You can use them if you have no letter left anymore (I guess that's rare), or if you have left no space on a drive (instead of buying a bigger drive) and you do not want to separate files belonging together in a single folder.

And in what situations could using mounted folders cause problems (compared to just use common partitions / drives)? What are the drawbacks of using them?

 

[USAFRet]

So what for can you use mounted folders at all, when does it make sense to use them? You can use them if you have no letter left anymore (I guess that's rare), or if you have left no space on a drive (instead of buying a bigger drive) and you do not want to separate files belonging together in a single folder.

And in what situations could using mounted folders cause problems (compared to just use common partitions / drives)? What are the drawbacks of using them?

I image it might be useful for a database application. The space where the data resides does not really need a "drive letter" for the database engine to see and use it.

Backup tools don't really need a drive letter either. Just a path.

Problems?
Well, I imagine it would be difficult to install a typical Windows application to some place without a drive letter.
Why you would want to do that, I don't know.

 

[hotaru.hino]

Mounted folders use a drive letter: the letter where the folder was created. So if you have a partition and mount it to C:\Foobar, you access it with the path "C:\Foobar"

I guess one problem is you can't append an existing folder with a partition. The mounted folder path must be empty when you create it and mount a partition to it. So if you're running out of room in C:\ to install programs, you can't say mount a partition to Program Files to streamline installing more programs.