MySQL Fatal Error MySQL Error!

The Error returned was:
Can't create/write to file '/tmp/#sql_6cb_1.MYI' (Errcode: 28)

Error Number:

Warning: Unknown: open(/var/lib/php/session/sess_h9a0ib0poiss7st512nl34c6n5, 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 (/var/lib/php/session) in Unknown on line 0