Linux disk full or no space left on device

Prove which filesystem is full, check inodes, then rank directories and files before deleting anything.

Safest first command

df -h

Before you run this

Expected output: Mounted filesystems with size, used, available, use percentage, and mount point.

When not to use it: Do not start cleanup from this page if you already know a database, volume, or backup job is actively writing; capture service-specific evidence first.

Expected output example

Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        50G   49G  900M  99% /
/dev/vdb1       100G   42G   58G  42% /srv/data

How to read the result

Start with the mount point at the highest Use%. Clean inside that mounted filesystem, not the path where the application happened to report the error.

Fast path

Start with mount-level evidence. Disk-full symptoms often appear in an application path, but the full filesystem may be root, /var, /boot, a Docker volume, or a mounted data disk.

df -h
df -i
du -xhd1 /var 2>/dev/null | sort -h

Do not delete random large files

Large logs, databases, uploads, backups, and Docker layers each have different cleanup paths. Rank first, then identify ownership and service impact.

Common causes

Large logs under /var/log
Package cache or old kernels
Docker images, layers, volumes, or container logs
Backups or uploads stored on the wrong mount
Deleted files still held open by a running process

What not to change yet

Do not delete files from /usr, /var/lib, /boot, or Docker volumes until you know what owns them.
Do not run cleanup commands before checking bytes, inodes, and deleted-open files.
Do not assume the largest file is safe to remove.

platform notes

Distro and service notes

Debian/Ubuntu

APT cache and old kernels can be part of the cleanup path, but inspect first.

Docker

Docker disk pressure needs Docker-specific inspection before prune commands.

systemd journal

Journal cleanup should come after checking journal size and retention needs.

supporting commands