MySQL Error!

The Error returned was:
Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

Error Number:

Warning: Unknown: open(/tmp/sess_rh1nu4f9aqq8i0ctdrdbcbkij5, O_RDWR) failed: Disk quota exceeded (122) in Unknown on line 0 Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0