vBulletin Datastore Cache – using Memcached cache to reduce MySQL database load
Day 2 – 24hrs later cache hits/second increased quite a bit when you take into account ~8hrs downtime for SSD upgrade and troubleshooting NFS share service issues. So roughly, after 48hrs, 217.5 million cache hits were made to the 4x Memcached v1.4.5 servers which is ~1,256 cache hits/second. Day 2 minus ~8hrs, averaged 2,020 cache hits/second.
Day 3, 72hrs laters, a total 435.7 million cache hits made to 4x Memcached v1.4.5 servers which is around 1,678 cache hits/second over 72hrs. Approximately, 218.2+ million cache hits were made in the last 24hrs. That’s 2,525 cache hits/second! Why the increase ? vB client added 2 more vBulletin v3.8.x based forums to the server along with the existing vB 4.1.2 forums – 3 forums combined amount to 28+ million posts and 300+k members.
Restarted the 4xMemcached v1.4.5 servers and here’s first 24.85hrs – 310 million cache hits at 3,464 cache hits/second ! MySQL still was pushing out around 397 queries/second though. The client broke their previous max vBulletin users online though on their vB 4.1.2 forums surpassing the 6,000+ vB users online mark at default vB session timeout of 900 seconds.
The vB client’s forums have been running very well now – for 253+ hrs of 4x Memcached servers caching hits from MySQL server – the total cache hit count is 2.627 billion memcached cache hits which is ~2,884 cache hits/second !