filesystem mounted at / has no free disk space help

Hi everyone and forgive me if this has been said before i have checked but cant seem to find the answer my self.

Im running Operating system CentOS Linux 7.4.1708
CPUIntel® Core™ i5-3570S CPU @ 3.10GHz
Number :4Cache :6144 KBSpeed :3424 MHz
RAM2 x 8192 MB
Disks1 x 2000GB SATA

Filesystem Type Size Used Avail Use% Mounted on /dev/sda2 ext4 20G 19G 0 100% / devtmpfs devtmpfs 7.8G 0 7.8G 0% /dev tmpfs tmpfs 7.8G 0 7.8G 0% /dev/shm tmpfs tmpfs 7.8G 1.4G 6.5G 17% /run tmpfs tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup /dev/sda3 ext4 1.8T 1.2G 1.7T 1% /home tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/0

all seemed fine untill last few months

i have error Warning! The 19.53 GB filesystem mounted at / has no free disk space!

i checked files say over 50mb and got these:

0 /proc/kcore
0 /sys/devices/pci0000:00/0000:00:02.0/resource2
0 /sys/devices/pci0000:00/0000:00:02.0/resource2_wc
13G /var/log/bandwidth
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-0000000004777933-000562e80651556f.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000047895dd-000562eb3c2d08ed.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-000000000479ab8d-000562ef903f3c8b.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000047abb51-000562f4a552bb72.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000047bd2c1-000562f819854b4b.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000047cdfef-000562facafbedfe.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000047efc4a-000563006ef1cbeb.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-0000000004800a65-00056302c8f67041.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000048118bc-00056305639f00e4.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-00000000048228d6-00056307c8141b37.journal
56M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c648e2fb0716ac58f83-0000000004833654-0005630a22d7b29d.journal
62M /var/lib/clamav/main.cvd.broken
64M /run/log/journal/2d406ad2c45e4e1b86f11fa56e394d32/system@5f66f3abe8704c6 48e2fb0716ac58f83-00000000047deca6-000562fd7500194b.journal
89M /var/log/btmp-20180101
102M /usr/lib/locale/locale-archive
105M /var/lib/clamav/main.cvd.rpmsave
139M /var/lib/rpm/Packages
142M /root/home.tgz
294M /var/lib/clamav/main.cld

i assume i cant just delete the 13G /var/log/bandwidth file
as seems i need to 1st make some more space and 2nd stop it happening again

any help much appreciated

Getting the same warning today on a Debian system.

Any help or hints available?

I have the same problem, trying to figure out how to increase space or get rid of files that are not needed

Reserved space for root user. Free space is free space for the un-privileged user, not total free space. Linux doesn’t display negative free space, unlike some other UNIX systems, when you start eating up root’s reserved space. Short version: Use ls of to find the file that is un linked but still open. Restart the application holding the file (or the whole system, if you are lazy) and you will get your free space back.
Long version: Most likely you have a file that is open by an application and being written to, but has been un linked (deleted) from the file system. so if you have any query visit and get the help.