It’s mentioned in passing, but by changing how they replicate indexes to their search servers Etsy managed to take their site offline.
Many of you probably use BitTorrent to download your favorite ebooks, MP3s, and movies. At Etsy, we use BitTorrent in our production systems for search replication.
Search at Etsy
Search at Etsy has grown significantly over the years. In January of 2009 we started using Solr for search. We used the standard master-slave configuration for our search servers with replication.