![]() ![]() The Varnish Massive Storage Engine (MSE) is an advanced stevedore that handles storage of cached objects and their metadata, keeping track of object relevancy and purging decisions. It has a greater understanding of how to best organize memory in different situations, taking over from the kernel the management and allocation of virtual memory and object replacement. Varnish is closely aligned with modern hardware, allowing users to make more efficient use of higher memory densities. We’ve seen Varnish servers handle 300,000 req/sec, so it comes into its own when dealing with the traffic commonly experienced by websites today. One reason for this performance and efficiency boost is that Squid is a single process running on one CPU core, while Varnish is heavily threaded and each client connection is handled by a separate worker thread. After deploying Varnish Enterprise, RTÉ could reduce the number of servers in use while handling 10x more traffic, with significant improvements in both response time and availability. They ran a large network of Squid servers but could only serve around 800 req/sec per server before performance degraded. In a case study, RTÉ, the national broadcaster of Ireland, told us that Squid wouldn’t scale their website. Many of our content delivery and broadcasting partners have made similar transitions from Squid to Varnish Enterprise. The Varnish code was then open-sourced to share these benefits. Varnish handled the same traffic with 3 servers, simultaneously lowering average page loads from >150ms to under 30ms. The Varnish project began with the need to improve this hardware efficiency and performance while coping with high traffic. Verdens Gang, Norway's largest online newspaper, grew to over 45 million page views per week, requiring 12 Squid servers even as page loads remained unacceptably slow. ![]() Varnish’s origins relate to an issue with Squid regarding performance and stability: two critical topics for modern web applications with high levels of traffic. It is true that, as well as the reverse proxy use case, Squid’s philosophy is to support many use cases and protocols, and it has a good track record in this regard, as well as stability and security. That’s not to say that Squid is a poor reverse proxy, but the fact it wasn’t specifically designed for HTTP acceleration is something to keep in mind when thinking about performance and features. Squid is a forward proxy that can be configured as a reverse proxy, while Varnish is built specifically to be a reverse proxy and HTTP accelerator. Varnish and Squid have fundamentally different caching architectures. But how do they compare? Which one is right for your web service? When you think of caching proxies and software for speeding up your website, you think about Varnish and Squid. ![]()
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