Windows 10: Unknown System (Z:) Partition or Disk.

Original Title: System (Z:) Partition or Disk?

I was getting an external hard drive in when I noticed a SYSTEM (Z:) drive. It's 359 MB. Not sure what it is, but nothing has access to it. I can't seem to get over what it is, although it could be potential backup software. Anyways, is there any way I can get rid of it? I don't really need something like that, although it's taking that little of my space. Thanks!

 

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Last updated October 3, 2019 Views 75,351 Applies to:
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Well. I have a lot of technical experience but why in the world windows has to create a partition I have no idea. I experienced the same issues that you all did. Drive Z appears for no apparent reason, denied access. No security tab to take ownership and gain access. Sooooo, I took control of my own problem...

I enable the raw administrator. Then opened a command prompt as administrator (probably could have did this without enabling the raw admin, but why take chances. Yes I'm the same guy that brings a tank to a knife fight.) I found the following on the root of the drive.


Z:\>dir
 Volume in drive Z has no label.
 Volume Serial Number is 7A95-624B
 Directory of Z:\
09/05/2016  07:10 PM    <DIR>          EFI
               0 File(s)              0 bytes
               1 Dir(s)     170,754,048 bytes free

in that folder I found:

Z:\EFI>dir
 Volume in drive Z has no label.
 Volume Serial Number is 7A95-624B
 Directory of Z:\EFI
06/27/2016  10:52 PM    <DIR>          .
06/27/2016  10:52 PM    <DIR>          ..
06/27/2016  10:52 PM    <DIR>          Microsoft
06/27/2016  10:52 PM    <DIR>          Boot
09/05/2016  07:10 PM    <DIR>          HP
               0 File(s)              0 bytes
               5 Dir(s)     170,754,048 bytes free

Z:\EFI>

Question, why in the %$@! is this partition a boot partition???

Next I ran disk management and got

two part ions that do not have a drive letter or a name. One of them matches the size of this drive Z so that the one were after. It says its a EFI system part ion, this would make sense (remember the root has a directory called EFI).

What is a EFI partition? Lets ask Google (Google knows everything).

Per Wiki:

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The EFI system partition (ESP) is a partition on a data storage device (usually a hard disk drive or solid-state drive) that is used by computers adhering to the Unified Extensible Firmware Interface (UEFI). When a computer is powered up and booted, UEFI firmware loads files stored on the ESP to start installed operating systems and various utilities. An ESP needs to be formatted with a file system whose specification is based on the FAT file system and maintained as part of the UEFI specification; therefore, the file system specification is independent from the original FAT specification.[1][2]

ESP contains the boot loaders or kernel images for all installed operating systems (which are contained in other partitions on the same or any other local storage device), device driver files for hardware devices present in a computer and used by the firmware at boot time, system utility programs that are intended to be run before an operating system is booted, and data files such as error logs.[

in a nut shell this partition should NEVER have appeared on your device/pc. Oh it should exist on it, but it is supposed to be hidden. So the question becomes why is it appearing? I smell a bug. 

Microsoft.. am I right?

By the way. A reboot made my drive go back into hiding.  I was happy, I told it "STAY THERE OR NO MORE TREATS FOR YOU!!!"

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Hi Thomas,

Thank you for posting your query on Microsoft Community.

I understand that you are facing issues with Windows 10. I apologize for the inconvenience caused to you.

The Z drive could be a system recovery drive or some other drive which you don't have access to it.

To assist you better, please provide us the below information:

  • When you say that "Not sure what it is, but nothing has access to it", are you getting any error message while trying to access the Z drive?
  • When you say that "external hard drive in when I noticed a SYSTEM (Z:) drive", have you noticed the System Z drive in the File Explorer?
  • Are you logged in as Administrator account? 

I suggest you to check whether the System Z drive is a System recovery drive or some other drive.

1. Click on Search bar.

2. Type "diskmgmt.msc" without the quotes in the search bar and click on it.

3. Then check description of the Z drive. Also check whether Z drive is recovery drive or System Drive.

Reply to us with the information, so that we can assist you better.

Let us know if you need any further assistance on Windows related issues and we will be glad to help.  

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