Written 5 Sep 2026. This is a how-to, not a product card.

When the computer's disk is full

Photos won't copy, the share says no space, or df shows the system disk packed. Confirm it is the computer (not the backup stick), free room or move the house folder, then retry. You don't need a NAS.

Haven't made a share yet? Start with a file share. Only checking room before anything fails? That quieter look is see if the computer still has room. Backup stick full instead of the computer? That is when the backup USB is full. This note is for the live disk that holds the OS and (usually) the house folder.

Skip until copies fail or Use% is ugly

Copy the exact line. No space left on device, Finder saying the disk is full, or a phone copy that stops mid-batch belongs here. A share that won't open for login or path reasons is not "full." That wider walk is when the house share won't open. Don't buy a NAS because one small SSD filled up with photos.

What this is

The house folder grew on the same disk as the OS. An old OptiPlex or laptop SSD fills faster than people expect. Phones keep dumping camera-roll photos until writes fail. Sometimes free gigabytes look fine and copies still fail: that is file slots (inodes), not bytes. The checks below separate a packed system disk, a packed house folder on a USB that stays plugged in, a backup stick problem, and an inode trap before you delete anything useful.

Step 1: awake, then SSH

Power light. Fan. If it looks asleep, start with is the computer still on?. You need SSH from the couch: SSH from the couch. Connect fails? when SSH won't connect.

Step 2: see which disk is full

Print human sizes:

df -h

Point at the line that ends in /. That is the system disk. Look at Use% and Avail. 95–100% (or tiny Avail) on / means the computer itself is the problem.

If the house folder already lives on a USB that stays plugged in, also check that mount:

df -h /srv/share

A line with a USB device under Filesystem means the live share is on that stick, not on /. Full USB share path: still this page (free room or bigger stay-in stick). Full /mnt/backup stick you unplug for backups: when the backup USB is full.

Step 3: rule out fake "full"

Copies fail but df -h / still shows plenty of free space? Check file slots:

df -i /

If IUse% is near 100%, you ran out of inodes (lots of tiny files), not gigabytes. That look is when copies fail but free space looks fine. Fix that path before you buy a bigger drive.

Step 4: see what is eating the disk

House folder size:

sudo du -sh /srv/share

Top-level folders on the system disk (biggest at the bottom):

sudo du -h --max-depth=1 / 2>/dev/null | sort -h

Finer walk when you already know it is tight: see which folders are eating the disk.

Common junk that is safe to clear after you recognize it:

Old package downloads: clear old package downloads when the disk is tight
Old logs: clear old logs when the disk is tight
Downloads / Trash on a laptop that still has a desktop user: du -sh ~/Downloads ~/.local/share/Trash 2>/dev/null

Do not delete /srv/share to "make room" unless you already have a second copy you trust: a backup of the house folder.

Step 5: pick one fix

Situation	What to do
Junk and logs are the bulk	Clear apt leftovers and old logs (links above). Empty Trash / Downloads you don't need. Re-check `df -h /`.
House folder is huge; system SSD is small	Park the live share on a USB disk that stays plugged in: put the house folder on a USB disk. Same share name for phones and laptops.
Live share already on a stay-in USB that filled	Delete obvious junk inside the share you recognize, or move to a bigger stay-in disk with the same house-folder-on-USB walk. Keep a second copy elsewhere first.
Only the backup stick is full	Wrong page. Go to when the backup USB is full.
Inodes full, bytes free	When copies fail but free space looks fine.

Deleting inside the share (only after you know what it is):

rm -ri /srv/share/some-old-folder

Ask first. Skip rm -rf /. Skip wiping the only good backup to free the live disk.

Step 6: confirm room, then retry the copy

Check again:

df -h / /srv/share

Leave headroom so next week's photos don't fail on day one. Retry the phone dump: save phone photos to the house share. Or open from a laptop: open the house share from a laptop. If the share still won't write after room returns, match the error on when the house share won't open.

Still no second copy of the house folder? Make one before the disk gets interesting again: a backup of the house folder.

What this is not

This is not a reason to buy a NAS tonight. It is not RAID. It is not a cloud plan until a plain second copy exists on a stick or another old PC. It is not deleting the only backup to free the live disk. It is not the backup-stick-full page (that is when the backup USB is full).

What next

Quieter check before anything fails: see if the computer still has room. Where the bytes went: see which folders are eating the disk. Move the live share off a tiny SSD: put the house folder on a USB disk. Second copy: a backup of the house folder. Backup stick packed: when the backup USB is full. Share open errors that are not disk: when the house share won't open. A dedicated file box is later: a first file box (NAS).

Skip

Skip buying a NAS because one small SSD filled up.
Skip RAID. RAID is not a backup.
Skip deleting the only backup to free the live disk.
Skip rm -rf on paths you have not listed with du first.
Skip treating a full backup stick as a full system disk.
Skip filling an old laptop with a movie library "just for now."

Sources

Debian: df. Debian: du. Ubuntu: df. Ubuntu: du. Official pages only. For the share this unblocks, see a file share. For the quiet room check, see see if the computer still has room. For moving the live folder, see put the house folder on a USB disk. For a packed backup stick, see when the backup USB is full.

Also on this topic

See if the computer still has roomAfter the house folder is working, check that the computer is not filling up. Photos stop copying when the disk is full. You don't need a NAS for this look. See which folders are eating the diskBefore you buy a bigger drive or a NAS, ask which folders are taking the room. Put the house folder on a USB diskMove the house share onto a USB disk that stays plugged into the old PC so photos don't fill the system drive. You don't need a NAS for this. When the backup USB is fullrsync says no space, or df shows the stick is packed. Confirm the mount, free room or use a bigger stick, or copy to another old PC. You don't need a NAS. When the house share won't openFinder, File Explorer, or the phone can't open the house folder. Check the computer is on, confirm the address, then match the error (path not found, login failed, can't write, disk full). You don't need a NAS. Save phone photos to the house shareCopy camera-roll photos from an iPhone or Android onto the house folder on the old PC. House Wi-Fi only. You don't need a NAS app or iCloud for this. A backup of the house folderA second copy of the house folder, on a USB disk you already have, or on another old computer. You don't need a NAS for this. When copies fail but free space looks fineBefore you buy a bigger drive or a NAS, check file slots when copies fail but gigabytes still look free. Clear old package downloads when the disk is tightAfter weekly updates, old downloads can sit on the disk. Clear them safely before you buy a bigger drive or a NAS.