I am using Debian. df -h shows me that I'm using around 275GB: Filesystem                 Size  Used Avail Use% Mounted onrootfs                     315G  274G   26G  92% /udev                        10M     0   10M   0% /devtmpfs                      6.4G  200K  6.4G   1% /run/dev/disk/by-label/DOROOT  315G  274G   26G  92% /tmpfs                      5.0M     0  5.0M   0% /run/locktmpfs                       13G  4.0K   13G   1% /run/shmI want to work out where the 274GB has gone. Following the answers here, I can see that around 50GB is being used by the filesystem: $ du -h /  --max-depth 3...51G     /I also happen to know that I have a large Postgres database, so I can go and check how much space it's using: $ psql => SELECT pg_database.datname, pg_database_size(pg_database.datname), pg_size_pretty(pg_database_size(pg_database.datname)) FROM pg_database ORDER BY pg_database_size DESC;   datname   | pg_database_size | pg_size_pretty-------------+------------------+---------------- mydatabase  |     230809349908 | 215 GB postgres    |          6688532 | 6532 kB template1   |          6570500 | 6417 kB template0   |          6562308 | 6409 kBSo there's about 215GB being used by Postgres, and about 50GB by the filesystem. But how can I check where the remaining 10GB has gone?It's not a big deal, but I'm just curious to know how one might track this down. 
Understanding where disk space has gone?
debian;disk usage