Install Solr 7 for Drupal 8 Search API on Ubuntu 16.04
A brief introduction to Search API Solr, an update on the ecosystem and how to get Search API 2.x working on a dev environment with multiple collections.
The df -h command shows the remaining space in human readable format.
If your disk is almost full (Use% column in the df -h result), you should go for the du command, see below.