Hi,
(We're running postgres 9.2.X)
The machine does have "high churn" on databases and have suffered a few crashes, is it possible for things to get left behind in $PG_DATADIR/data/base after recovery ? or am I possibly missing things still in use, that's reflected elsewhere ?
Additionally, the directory and it's contents haven't been touched in quite a while as well, and some of them do correspond to being touched at the machine having had a hard crash.
The reason I'm asking is that space used as reported by pg_database_size is off by a LOT compared to df on the filesystem (4-5TB as oposed to df/du agreeing on 9-ish TB).