How to check the used disk space of Google Persistent Disk without looking into each of them?
The workaround with snapshot size will work in the console.
For more precise (and quicker) detailed overview you can SSH into your instance and do:
sudo df -h
The response you get will look similar to this:
YOURUSERNAME@YOURINSTANCENAME:~$ sudo df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 9.8G 9.3G 0 100% / udev 10M 0 10M 0% /dev tmpfs 743M 81M 663M 11% /run tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sdb 197G 60M 197G 1% /mnt/new_disk
Entries starting with /dev/ under 'Filesystem' are your disks.
Just install Monitoring Agents in https://console.cloud.google.com/monitoring/dashboards/resourceList/gce_instance then check the dashboard