With vbulletin 3 + sphinx, we have sphinx running on the DB server, and it runs beautifully with 16 gigs of ram and SSD's. Server loads barely register . We have 13M posts, and from what I've read from @Slavik we'll need like 13 gigs of ram just for Elasticsearch? So we'd pretty much need to buy a new dedicated search server with this many posts? If so how robust should this server be?