I’d first recommend taking a look at Roles / Classes matrix, which will give you the nicer view of how and where the new roles will fit into the new processes. Overall, there’s been a trend of adding new types of things that can live in stateless class processes happily, so it’s always nice to have an extra few of them laying around.
data_distributor were both previously pieces of
master that got broken out to reduce master CPU usage (and to let them survive across recoveries). If you had a
master class process in your 6.0 cluster, then they’ll prefer to be there. Otherwise, they’ll migrate towards other
stateless class processes if they’re available and preferably unused.
log_router is the piece that pulls mutations from the primary to the secondary in a multi-region cluster. FDB will recruit a number of them that matches the number of transaction logs that you have, or you can configure it with
log_routers=N. As log routers are stateless, they’ll probably just use the processes that you have allocated to be the proxies/resolver/master/etc. in the secondary in the case of a failover, so I don’t really expect that you’ll need to allocate any new processes for them.
But the feedback that we didn’t update the documentation about configuration is appreciated.