---
title: Disk Space Low
category: Windows
summary: The system drive is almost full, causing slowness, failed updates or "not enough space" errors.
applies_to: Windows 10 / 11 and Linux
related: 02-slow-pc, 08-basic-linux-commands, 11-backups
---

## Symptoms

- "Low disk space" warnings, or a red drive bar in File Explorer.
- Windows updates or app installs fail with "not enough space".
- The PC is slow, can't save files, or apps crash.
- On Linux: "No space left on device" errors, services failing to write logs.

## Before you start

- Which drive is full (`C:` system drive or a data drive)? How much is free in total?
- **Don't delete things you don't recognise.** Delete only items you know are safe (Recycle Bin, temp files, the user's own downloads after they agree).
- Never manually delete files from `C:\Windows`, `C:\Program Files`, or `/usr` / `/etc` on Linux.

## Steps

### Windows

1. **See what's using space:** Settings > System > **Storage**. Click each category (Apps & features, Temporary files, Documents) to see sizes.
2. **Empty the Recycle Bin** (after confirming with the user).
3. **Remove temporary files:** in Storage > *Temporary files*, tick *Temporary files*, *Recycle Bin*, *Downloads* (only if the user agrees), *Windows Update Cleanup*, and click **Remove files**. Or run **Disk Cleanup** (`cleanmgr`) and choose *Clean up system files*.
4. **Turn on Storage Sense** (Settings > System > Storage > Storage Sense) so Windows cleans temporary files automatically.
5. **Uninstall unused programs:** Settings > Apps > Installed apps, sort by size, remove what the user confirms they don't need.
6. **Find big files:** sort the user's folders (Downloads, Videos, Desktop) by size in File Explorer. Free tools such as **WinDirStat** or **TreeSize Free** show a map of what uses space (check that your organisation permits installing them).
7. **Move or offload data:** move large personal files to an external drive or OneDrive. With OneDrive *Files On-Demand* you can right-click a folder > **Free up space** to keep cloud files online-only (only for files already synced; check the sync status is complete first).
8. **Shrink Windows system components (optional):**
    ```
    DISM /Online /Cleanup-Image /StartComponentCleanup
    ```
    (administrator Command Prompt; can take a while).
    Turning off hibernation frees the `hiberfil.sys` file but also disables hibernate and Fast Startup: `powercfg /h off` (reverse with `powercfg /h on`). Only do this if the user agrees.
9. **If the drive is still nearly full:** the PC may need a larger drive. Record the sizes and recommend an upgrade.

### Linux

1. **See which filesystem is full:** `df -h`. Also check inodes: `df -i` (a disk can be "full" because it ran out of file slots).
2. **Find the biggest folders** (stay on one filesystem with `-x`):
    ```
    sudo du -xh --max-depth=1 / 2>/dev/null | sort -h | tail -n 15
    ```
    Repeat inside the biggest folder (for example `/var`).
3. **Common safe cleanups (Debian/Ubuntu):**
    ```
    sudo apt clean                          # remove downloaded package files
    sudo apt autoremove                     # remove no-longer-needed packages (read the list first)
    sudo journalctl --vacuum-size=200M      # shrink the systemd journal to about 200 MB
    ```
4. **Large old log files** in `/var/log` can be compressed or rotated (`logrotate`); don't delete a log that a running service is writing to. Truncate it instead, if approved: `sudo truncate -s 0 /var/log/example.log`.
5. **Deleted but still open files:** `sudo lsof +L1` lists deleted files still held by running programs. Restarting that program frees the space.
6. Re-check with `df -h`.

## Escalate when

- It's a **server** or shared storage, or a database/mail volume is growing quickly.
- The space is used by something you can't identify and aren't allowed to delete.
- Free space keeps dropping again within days (something is filling the disk).
- The drive reports errors or the PC needs a hardware upgrade.

## Ticket note template

```
Issue: Low disk space on <drive/mount> of <device>
Before: __ GB free of __ GB (__%)
Biggest users of space found: <folder/app> (__ GB), <folder/app> (__ GB)
Actions (with user's OK): emptied Recycle Bin | temp files / Windows Update cleanup | uninstalled <apps> | moved <files> to <location> | Linux: apt clean / journal vacuum
After: __ GB free of __ GB (__%)
Root cause: <e.g. large downloads, old logs, small drive>
Recommendation: <upgrade drive / enable Storage Sense / log rotation>
Next step / escalated to: 
```