Cacti 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

Summary:

Warning: Unknown: write 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 

Problem or Goal:

Not able to login to the cacti GUI with error as seen in the screen shot below:

Cause:

The root partition on the hard disk was full at 100%

Solution:

Free up some space on the root partition, i did this by emptying some log files, the biggest log file was "mysqld.log"

Empty this log file using the command below:

# cat /dev/null > mysqld.log

Restart the services:

[root@localhost log]# /etc/init.d/mysqld restart
Stopping mysqld:                                           [  OK  ]
Starting mysqld:                                           [  OK  ]

[root@localhost log]# /etc/init.d/httpd restart
Stopping httpd:                                            [  OK  ]
Starting httpd: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.localdomain for ServerName
                                                           [  OK  ]

[root@localhost log]# /etc/init.d/snmpd restart
Stopping snmpd:                                            [  OK  ]
Starting snmpd:                                            [  OK  ]

Problem Solved?

Yes, the login works fine and the cacti tool is back to normal.