If you use DirectAdmin and CentOS there are some times that you cannot take a backup and you receive the message:

gzip: stdout: Disk quota exceeded

First of all login via ssh and type:

example result:

Filesystem Size Used Avail Use% Mounted on
/dev/md2 1.8T 801G 925G 47% /
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 7.2M 16G 1% /dev/shm
tmpfs 16G 1.6G 14G 10% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/md1 488M 277M 185M 60% /boot
tmpfs 3.1G 0 3.1G 0% /run/user/0

 

Check for the partition home directory uses. In the above example is /dev/md2.

Then type

 

Check if limits removed:

Try backup again.