Was going through the server and deleting very old versions of compiled daemons and libraries; freed up ~5GB of space on the boot drive so far.

However, I found an old .tar image of the server 'www' data from September 6, 2023, taking up ~548 GiB on the www-data RAID setup. (The final one is .xz'ed, taking up ~449 GiB on the NAS.) Thought I purged it years ago, lol.

There's also some old HP laptop disk image on there from 2014 that I have never removed, taking up ~109 GiB; since copied to the NAS years later.

Another ~800 GiB used up there is a bunch of Teknoparrot ROMs just sitting there as well.

Very old versions of MySQL sit there; no longer can use them since the move to MariaDB.

There's more decade [plus]-old cruft on that setup that existed ever since the server used a 4x 250GB RAID0+1 setup in the early 2010s. Removing a lot of it would free up probably ~2TiB of space.