This means the specific drive (volume or partition) will have its drive letter removed and no longer be automatically mounted and assigned a drive letter whenever connected to the computer until you manually mount it again. If you unmount a drive, Windows removes the volume mount point from the specified directory, dismounts the volume, and makes the volume not mountable. Whenever you reconnect a drive to the computer, it will always use the same drive letter it was last assigned or changed to. On systems with a lot of storage you will often run out of drive letters for your partitions and volumes. This ensures Windows can always uniquely identify a volume, even though its drive letter has changed. When you add or connect a new volume (disk or drive), Windows will automatically mount it with an assigned drive letter by default.Įach drive (volume or partition) will have an unique Volume GUID assigned to it by Windows. How to Mount and Unmount a Drive or Volume in Windows