[Tile-serving] OSM-bright optimization

[Stephen D]

Hello,

I'm having trouble getting osm-bright to render at a reasonable speed. 
It takes over an hour to render some tiles! The bottleneck is I/O - My 
CPU hovers at only a few percent. This is specifically with low-Z tiles 
- higher Z tiles are fine, but the problem is once a low Z tile has 
started being rendered, it slows the server down to the point that no 
tiles can be rendered in a reasonable time.

osm2pgsql ran out of space when generating indexes, so I did a second 
import of a much smaller set into a different DB. There were 2 missing 
indexes in the first import so I manually recreated them. Is there 
anything I could have missed?

The server has a 1TB SSD, 64GB of RAM, and 8 cores/16 threads of CPU.

My postgres config has the following settings:

shared_buffers = 32GB

work_mem = 2GB

maintenance_work_mem = 4GB

effective_io_concurrency = 500

max_parallel_workers_per_gather = 2

random_page_cost = 1.1


Thanks!

Stephen