My SSH df -h
Filesystem Size Used Avail Use% Mounted on
/dev/xvda3 7.2G 6.5G 407M 95% /
/dev/xvda1 99M 23M 71M 25% /boot
tmpfs 128M 0 128M 0% /dev/shm
/usr/tmpDSK 485M 11M 449M 3% /tmp
du -sh /*
It seems that i have a problem in / but how can i access it?
The root "/" partition size appears to be too small in comparison to the needs of how much data is being stored there. Based on the output provided, it would appear to me that your "/home" directory path, that usually contains the majority of account data from hosted sites and users, as well other sizable areas, like "/usr", are all being stored within the root "/" partition on your server.
I recommend adding another disk drive to relocate some of the data, such as relocating the "/home" directory to its own partition on a new hard drive so that space is freed and made available on the existing root "/" partition. Your upstream server or hosting provider can assist with installing and provisioning more hard drives for expanded storage capacity.
If adding hard drives is not an option, in my professional opinion, I would consider migrating to a new server that uses a significantly larger root "/" partition in addition to using a separate hard drive or larger partition to store the "/home" directory.
cPanel, by default, creates a loopback device that mounts to /tmp. The default size is only 512MB. This is quite small and quite common for a cPanel server to need a larger /tmp partition.
I see no information that would indicate an issue with the "/tmp" partition; the detail provided leads me to believe the reported problem stems from the small size of the root "/" partition and the increasing disk usage requirements of the affected system.