MySQL Error!

The Error returned was:
Access denied for user 'root'@'localhost' (using password: YES)

Error Number:

Warning: Unknown: open(/var/tmp//sess_60l0dn513kfuhg8pu5ernf30i6, O_RDWR) failed: No space left on device (28) 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 () in Unknown on line 0