Disk Space is Increasing Unreasonable (tmpfs /run/log/journal)

Dear All,

I'm facing a disk space increase after installing ISPconfig, and no website installed.
More in specific, I noticed that only the tmpfs /run is increasing the disk space.

Code:

root@vpsXXX:~# df
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/vda1       10287416 2492900   7354392  26% /
udev               10240       0     10240   0% /dev
tmpfs             401908   45628    356280  12% /run
tmpfs            1004768       0   1004768   0% /dev/shm
tmpfs               5120       4      5116   1% /run/lock
tmpfs            1004768       0   1004768   0% /sys/fs/cgroup
tmpfs             200956       0    200956   0% /run/user/0

The directory which is increasing is /run (/run/log/journal) but even if it's just 41Mb, the Disk usage seems to be 12% of 10gb.

I'm not understanding exactly what's happening, have you ever face it before?
Is ISPconfig doing so?
In the machine is installed ISPconfig and Squid3 (which is not used for cache, but just like a browser proxy).

Thanks