Steps to increase /tmp size on cPanel dedicated servers
Step 1: Stop all services
/etc/init.d/mysql stop
/etc/init.d/httpd stop
/etc/init.d/cpanel stop
/etc/init.d/lsws stop
Step 2: Unmount the /var/tmp and /tmp
umount -l /var/tmp
umount -l /tmp
Step 3: Take the backup of the file /usr/tmpDSK to take the backup of existing data
mv /usr/tmpDSK /usr/tmpDSK-bk
Step 4: Update the new size of /tmp in the file /scripts/securetmp
vi /scripts/securetmp
Change the value of the variable $tmpdsksize to required size.
Step 5: Run securetmp script
/scripts/securetmp
Step 6: Start all the services again
/etc/init.d/mysql start
/etc/init.d/httpd start
/etc/init.d/cpanel start
/etc/init.d/lsws start
Step 7: Confirm that all services are working fine and confirm the change size of /tmp by command
df -h