Wikimedia Maps/Tile generation report

Introduction
The map infrastructure store vector-tiles in a Cassandra DB and can store data from zoom levels 0 to 15 where each zoom level has 2zoom tiles. Tilerator generates 22 tiles per second in average for each CPU available. Generating the whole planet can take more than a month for 24 CPU's.

Debian upgrade to stretch
Because of the Debian upgrade to stretch, OSM data needed to be reloaded and all tiles needed to be generated from scratch. The tile generation started at 10/22/2018 and it's an ongoing process until now (last update was 12/19/2018). After some delay on tile generation we started keeping log through time regarding the tile generation health using a node tool that collect metrics generated by Tilerator, which can be seem in the following table:

Useful Commands
The following Tilerator command was used to schedule and queue tile generation jobs:

Problems during tile generation

 * Tile generation for zoom levels 14 and 15 failed. Tilerator tries to run jobs with too much tiles and got the error.
 * Solution: restart jobs using Tilerator UI