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The output of your command "$ df -h" is:

Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv  689G  118G  543G  18% /
tmpfs                               12G  168K   12G   1% /dev/shm
tmpfs                              2.4G  1.5M  2.4G   1% /run
tmpfs                              5.0M  8.0K  5.0M   1% /run/lock
/dev/sda2                          2.0G  307M  1.5G  17% /boot
tmpfs                              2.4G  108K  2.4G   1% /run/user/131