HDD Refuses to Mount on the Machine that Initialized It

A year or so ago, I purchased five 2TB WD Black Enterprise Storage HDDs

When I first received them, I initialized them, provided names and drive letters, and put them through a few copy/read/write tests to insure that all was well.

I did this using my Inateck toaster-style dual HDD adapter thingie.

I copied an entire years worth of photos and their folder tree structure onto each HDD and left them there.

Once I was satisfied all was well, I put the HDD in question in an Inateck HDD storage box and stored it safely away for future use.

Now, I need to put it to use.

I popped it in my toaster thingie and it shows up in Disk Management as "Offline" ; the label is correct but no drive letter.

The options are all greyed out and Disk Management won't allow me to do a thing.

I fired up EaseUS Partition Master, that is usually able to fix things when Disk Management won't even try.

When I attempt to add a drive letter, EaseUS Partition Master tells me "Unable to Mount Volume"

I tried the HDD in my front-loading HDD bay that is SATA-connected to the motherboard = still no go.

I installed it in an Inateck external enclosure and still no go.

All of this on the machine that initialized the disk and added the name and letter.

I moved the Inateck enclosure over to another Windows 7 machine and it immediately recognized it and all worked as it should without any need to mess with disk management tools.

Various other 2TB WD Blacks are working fine in all the ports/enclosures/bays where I tried the problem disk.

There is obviously nothing wrong with the HDD, it just will not mount in my machine.

How am I going to fix this ?

Thanks for reading.

Is your computer the Dell Optiplex 780m "mini-tower"?
Did you initialize the drives as MBR or GPT?

I can't think of any reason for your computer not mounting the drives, only a antivirus blocking access until full scan is complete.

BuckSkin said:

I popped it in my toaster thingie and it shows up in Disk Management as "Offline" ; the label is correct but no drive letter.
The options are all greyed out and Disk Management won't allow me to do a thing.....

Various other 2TB WD Blacks are working fine in all the ports/enclosures/bays where I tried the problem disk....

I moved the Inateck enclosure over to another Windows 7 machine and it immediately recognized it and all worked as it should

There is obviously nothing wrong with the HDD, it just will not mount in my machine.....

Megahertz07 said:

I can't think of any reason for your computer not mounting the drives....

I can, a disk signature collision. If so then it would explain why the drive can mount in any other machine, just not in the one that already has a drive with the same signature, as in this thread....

Two Seagate External Drives, one not recognised

Megahertz07 said:

Is your computer the Dell Optiplex 780m "mini-tower"?

Yes and thanks.

Bree said:

I can, a disk signature collision. If so then it would explain why the drive can mount in any other machine, just not in the one that already has a drive with the same signature, as in this thread....

Two Seagate External Drives, one not recognised

Disk ID collision was exactly the problem.

I never knew until now that I could mouse over "Offline" and get the ID collision message; I may never have figured that out on my own.

I followed the instructions in the provided link and the links within the links; and, sure enough, I had two disks with identical IDs.

This really puzzles me as when I had all five up and running when I first got them, there was no collision then.

Luckily, before I got as far as using diskpart, I had already turned off all of my multitude of external disks; so, I only had the problem disk and the internals to deal with.

The conflicting disks had eight digits/characters ending with "4" ; instead of only changing one notch to "3" or "5", I changed the last character of the problem disk to "9".

Once I got this done and exited diskpart, disk management was still showing it as conflicting (it was not; we'll get to that in a minute) ; so, I went one-by-one, listing the ID for every connected disk and there were no conflicts.

Looking over the IDs of all of the disks, if someone randomly created an ID for a disk and ended up with a conflict, they should run and buy a lottery ticket and pick their own numbers --- it is that unlikely that you could ever accidentally create a conflict.

I am just anxious to see what happens when I start adding all of my other disks that I turned off into the mix.

Two things that would sure be helpful:

1. If there were a diskpart command to show the two conflicting disks instead of having to go through the motions of checking them one-by-one.

2. If diskpart provided more means of identifying the listed disks, such as including drive letters and volume names; it is impossible to identify a particular disk from several same brand/same size disks --- at least it is not obvious to me.

Okay, although I had changed the uniqueid of the problem disk, and checked and rechecked that the ID had actually changed, exited diskpart after each investigation, exited and restarted disk management several times, my newly identified disk was still showing as a conflict.

The fix was as simple as switching off the enclosure and then switching it back on; --- once it made the "KerThunk" noise of a new USB connection, an Explorer window opened and there was my disk/volume, complete with a drive letter and ready for action.


I very much appreciate you guys input and Bree for providing the solution to my situation.

This has been a learning experience for me.

BuckSkin said:

Disk ID collision was exactly the problem.....
I very much appreciate you guys input and Bree for providing the solution to my situation.
This has been a learning experience for me.

Glad I could help.

Megahertz07 said:

did you clone one of your computer drive into the five drives?

No; when I was initially testing them, I copied a years worth of photos on each of them and tested for read/write and corruption.

Three of the disks have been in action ever since then with no issues.

I just left the photos on the two disks that I stored, one of them being the problem disk in this situation.

Megahertz07 said:

And all five drives with same disk signature collision?

No; so far, just the two had somehow acquired identical IDs.

Megahertz07 said:

If the drives were created and loaded on same computer, and were working and now aren't, what changed?

I have no idea how it happened; it sure was a mysterious surprise to me.


I still have one of the five disks stored away.

I am curious now to see whether it is going to conflict or not when I try it.

Once I get past a problem, it seems like I never have that same problem again --- "Okay, I have dealt with this before and I know exactly what is going on and how to fix it" --- it is just one mystery after another.

SIW2 said:

If there are two disks with the same sig, windows will not automatically bring the second disk online. If you rt click and select online, windows will bring the second disk online and change the sig.

It is not hard to do.

Where is this right-clicking done ?

In my situation, everything in the disk management right-click menu was greyed out and unresponsive.

The disk would not show up anywhere else.

Do I right-click the little area where is says the disk is offline ?

Thanks.