"Secure" Service Tier
secure.phabricator.com is currently 4 hosts. This setup was to test repository clustering and database partitioning, and is not load related. secure can be scaled down to one host.
secure002 and secure004 are likely easy to take out of service, since they're pure replicas. Repositories can be stripped off secure003 easily, but the writable Files master database is on that host and the datasize isn't trivial (~8GB). This is probably easiest to deal with by just taking down services, dumping and moving the data, and accepting a couple hours of downtime.
The services on secure could conceivably be merged to admin, although I think the bootstrapping problem this creates is probably not worthwhile.
I'm planning to simply delete the Discourse forum without preserving any content. I think most of the useful content (e.g., bug reports with reproduction instructions) made it upstream, and the stuff that didn't make it upstream is largely not worth preserving.