Mounted devices

The mounted devices settings are stored in the key:

HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices

Seen on:

  • Windows 2000

  • Windows XP

  • Windows 2003

  • Windows Vista

  • Windows 2008

  • Windows 7

  • Windows 8.0

  • Windows 8.1

  • Windows 10

  • Windows 11

Values:

Name Data type Description
%IDENTIFIER% REG_BINARY

Where the following variants of %IDENTIFIER% have been observed:

  • “\DosDevices\C:”

  • “??\Volume{01234567-89ab-cdef-0123-456789abcdef}”

Where the value data consist of either:

  • Device string value data

  • GPT partition value data

  • MBR partition value data

Device string value data

The device string value data is variable of size and consists of:

Offset Size Value Description
0 ... UTF-16 little-endian encoded string, without an end-of-string character

For example:

\??\FDC#GENERIC_FLOPPY_DRIVE#6&12345678&0&0#{01234567-89ab-cdef-0123-456789abcdef}
\??\IDE#CdRomQEMU_QEMU_DVD-ROM_______________________1.6.____#5&12345678&0&0.1.0#{01234567-89ab-cdef-0123-456789abcdef}
\??\SCSI#CdRom&Ven_VBOX&Prod_CD-ROM#4&0123456&0&010000#{01234567-89ab-cdef-0123-456789abcdef}
_??_USBSTOR#Disk&Ven_Generic&Prod_Flash_Disk&Rev_8.07#01234567&0#{01234567-89ab-cdef-0123-456789abcdef}

GPT partition value data

The GPT partition value data is 24 bytes of size and consists of:

Offset Size Value Description
0 8 "DMIO:ID:" Signature, where DMIO is presumed to refer to Disk Manager I/O Driver
8 16 GUID Partition Table (GPT) partition identifier (little-endian GUID)

MBR fixed-disk value data

The MBR partition value data is 12 bytes of size and consists of:

Offset Size Value Description
0 4 Master Boot Record (MBR) Disk identity (signature) (also referred to as disk identifier)
4 8 Offset of the partition, in bytes, that contains the previously mounted file system

Notes

The mountvol.exe Windows CLI tool can show information about mounted devices.