login not possible; Message "systemd-journald: failed to create new system journal: no space left on device"

[nordlicht]

I unsuccesfully tried to login to my proxmox instance remotely. I was quite sure that my password was correct, but I had to drive to the physical machine, which showed the message

systemd-journald: failed to create new system journal: no space left on device

After hard reset and reboot, the message was gone and I could login again.
Questions:
- Where can I find the logs which caused this problem?
- What can I do to prevent this from happening in future?
- Can someone point me to existing documentation, which brings light into this situation?
Thanks in advance!

 

[harethl1s]

What's th output of this command?
sudo df -h

 

[nordlicht]

sudo df -h Filesystem Size Used Avail Use% Mounted on udev 12G 0 12G 0% /dev tmpfs 2.4G 1.1M 2.4G 1% /run /dev/mapper/pve-root 94G 83G 7.2G 93% / tmpfs 12G 46M 12G 1% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock /dev/sda2 511M 328K 511M 1% /boot/efi /dev/sdb1 2.8T 196M 2.7T 1% /mnt/sdb1 /dev/fuse 128M 20K 128M 1% /etc/pve tmpfs 2.4G 0 2.4G 0% /run/user/0