No space left on device

Get this error?

#: No space left on device

Check the free space:

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 3.3G 1.7G 1.5G 54% /

Still fine.

Check the inodes or i-nodes.

Whenever a file is created on a file system, an inode is used to contain information about the file. Most of file systems have a fixed amount of inodes number (which is set during the mkfs operation of the file system).To check the state of the inodes on a Linux system, you can use df –i.

df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sda3 216000 216000 0 100% /

It's usually from the mail service. It creates a lot of empty files (over 1 million files). Try to delete all its files first.

cd /var/spool
find clientmqueue -exec rm -rf {} +

Or you can count number of files and delete other files

All system
for i in /*; do echo $i; find $i |wc -l; done

Current location
# for i in *; do echo $i; find $i |wc -l; done

ETC directory
# for i in /etc/*; do echo $i; find $i |wc -l; done

TMP directory
# for i in /tmp/*; do echo $i; find $i |wc -l; done