Cacti webpage gives below error;
FATAL: Cannot connect to MySQL server on 'localhost'. Please make sure you have specified a valid MySQL database name in 'include/config.php' 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

Root directory partition is 100%, is it safe to empty mysqld.log file consuming 28G out of 38G? or can i reduce /home partition and increase root partition.. what would be the best solution?

Thanks

Stop MySQL first, then remove the log(s) in question, and restart it, and consider looking at logrotate to keep things like that from happening. And 'reduce /home partition' isn't an easy thing to do, unless you have LVM in place, and are also running LVM on your / partition as well...which you probably aren't. A 38GB root partition is very small these days.

will it effect the current graphs and configuration if i empty mysqld.log file? or its just a logs and would make no difference..

If you're concerned, then back up the logs/copy them elsewhere. But these are just MySQL log files, not the data that drives anything. Again, stop MySQL, and do as you wish with the logs, and again, look into using logrotate.

Thanks TB0ne,
Could you please let me know how can i backup logs and apply logrotate..
Regards

AGAIN: as said before, you can copy them elsewhere. How you do this and where you copy them to is up to you. And you can read the documentation on logrotate from their website and the many logrotate tutorials you can find with a brief Google search.

I copied the file into other directory after stopping service: service mysqld stop, then when i completed copying, i tried to start the services by command service mysqld start, its giving below error;
Timeout error occurred trying to start MySQL Daemon
Starting mysqld: [FAILED]

how can i get mysqld started again?

Regards..

Check our disk space again. If you copied that file to another folder on the same out-of-space drive, you've done nothing but relocate the problem. Also try running
...to see if that helps. Again, as you've been asked a couple of times now, why is your / partition so small? Have you tried to reboot? Did you check any of the system logs to see if there are any errors??

Read the "Question Guidelines" link in my posting signature; putting your exact error message into Google yields lots of suggestions/results.