My main Windows drive has suddenly started filling up even though I haven't downloaded anything recently. When it becomes full, I sometimes see a warning or error appear even while the computer is idle. Disk Management also shows two large drives—around 8 TB and 4 TB—that I never installed. One entry is labeled as a recovery partition, and I'm worried that deleting anything could stop Windows from booting. The real problem is the first drive, which contains Windows and required system files; it used to have plenty of free space but recently became almost full. What could be causing this, and which partitions or virtual disks are safe to remove?
3 Answers
First confirm whether the physical Windows drive itself is actually full, rather than relying only on the disk-management view. The unusually large 8 TB and 4 TB entries could be virtual disks or a Windows display issue, so check their properties and inspect what is using space on the system drive before deleting anything.
The unexplained disks may be caused by corrupted partition information, mounted virtual disks, or a Windows storage-management problem rather than newly installed hardware. Check Disk Management, Storage settings, and large folders such as Windows update data, temporary files, restore points, hibernation, and user profiles. Back up important files before making changes. If the layout remains corrupted and no cause can be found, moving your data elsewhere and performing a clean Windows installation from USB may be the safest reset, but delete partitions only after verifying which physical disk is which.
A clean installation may be my fallback. I’ll make sure to back up my files and identify the actual physical drive before removing any partitions.
A partition marked Recovery is normally created automatically by Windows and is used for recovery tools. It is usually small, and deleting it generally won’t free much space. Unless you have a specific reason to remove it, leave it alone—especially while troubleshooting.

The first drive is definitely the one filling up. It contains Windows and the files that need to stay on the system drive; it used to be below about 200 GB, so I’m trying to find what suddenly consumed the space.