Four and half years ago, I wrote a blog post about Varnish , a 'front-end proxy' for webservers. My best description of it then was as a protective bubble, analogous to how it's namesake is used to protect furniture. I've been using it happily ever since. But last week, I got to really put Varnish through a test when the picture here, posted by Fair Vote Canada (one of my clients), went viral on Facebook. And Varnish saved the server and the client in ways I didn't even expect. 1. Throughput Varnish prides itself on efficiently delivering http requests. As the picture went viral, the number of requests was up to about 1000 per minute, which Varnish had no trouble delivering - the load was still below 1, and I saw only a small increase in memory and disk usage. Of course, delivering a single file is exactly what Varnish does best. 2. Emergency! Unfortunately, Varnish was not able to solve a more fundamental limitation, which was the 100Mb/s network connec...