@Anonymous
Varnish is actually very popular among high-traffic websites:

"Varnish is used by a great number of high-profile, high-traffic websites including online newspaper sites such as The New York Times, BBC, The Guardian, The Hindu, social media and content sites such as Facebook, Twitter, Vimeo, Tumblr and many more. Of the Top 10K sites in the web, around a tenth use the software." Source: https://en.wikipedia.org/wiki/Varnish_(software)

This thread also lacks an simple explanation why Varnish would be useful (or I read past it, in that case, sorry).

In stead of running PHP code every time a page loads, Varnish lets Apache run the PHP code once en stores the website Apache produced in memory. The next time this saved page is shown, without the need of running PHP code. This way a server could serve a lot more pageviews per second.

Webshops and such are tricky, but it's very possible to get those to run without problems with Varnish.

@Ben: You dont seem to know what you are talking about. Varnish is something totally different than Spdy. Varnish is a caching reverse proxy server, Spdy is an alternative/addition to the HTTP protocol which makes for slightly faster webpages due to compression and optimalisations.

As I've written in this thread before, Varnish is _not_ a drop-in addition to Apache. Varnish needs to be configured to work properly with various CMS and shop software like Magento. Thus, the only way to achieve supporting Varnish is if Plesk is aware of the software running on a users website. This is way beyond the scope of Plesk.

I very much doubt that 'all major' sites use Varnish. I believe the use of Varnish is actually in decline and other solutions such as Redis object caching is now the more obvious choice. Redis is just an example, there are lots of other data stores that can be used to achieve better performance.

Your Website is much faster with varnish. Varnish is not about heavy load sites like Apache+Nginx its all about fast webpages. Its much faster than php based alternatives. All major sites using varnish or spdy. I don´t understand why Sergey closed this thread? The advandage of varnish is very easy to understand.

This is a shame.

Varnish do Full page cache, also many CMS support varnish like DRUPAL.

This is a shame and would have made plesk very attractive.

you can install varnish along side plesk.. you need to manually allocate the IP to nginx using the Listen command and reserver an IP for varnish. It should be simple to automate this in plesk

2 Rich Milns

Nginx has proxy capabilities, thought it benefits in the other way than Varnish does. Nginx doesn't cache - so DB and PHP are still loaded in terms of CPU. But Nginx helps Apache to end process faster (fast local connection) and thus save on RAM when multiple visitors (especially when visitors on mobile traffic). And Nginx is transparent, so it doesn't require site re-configured.

Not that Nginx fully replaces Varnish, but it handles high load problem from a different perspective

Unless I'm mistaken, I believe Varnish is more of a caching mechanism whereas Nginx is a higher performance HTTP server than Apache (please correct if I'm wrong here). It was my understanding that Varnish was higher performance than Nginx because it can cache entire web pages so that the DB server and PHP for example do not have to be hit on every request. It also features things like Edge Side Includes and ways of purging the cache using a PURGE HTTP request which is pretty nice from a developer point of view. It's great for high traffic sites, but needs quite a bit of extra configuration for each website it caches I believe. The question is: could Nginx be configured per domain to have some of the features that Varnish seems to offer?

Failover capabilities is not a valid reason. Only varnish does not give you actual failover, you need multiple servesr for that. There are other ways to achieve that using other Parallels' products.

Full page cache,
Also fail over capabilities

I think Varnish is becoming less and less usefull, as there are better alternatives. For Magento there is (for example) Redis, which is a better alternative to speed up your website.

Varnish is also complex to configure and might require different rules per website depending on the content. eg. magento requires its own set of Varnish rules, and WordPress might require yet another ruleset.

I feel Varnish is currently to complex to setup to achieve this in a matter where it is understandable for end-users.

I use it on a VPS but without Plesk Panel. The website flies! It's a huge increase in performance! It would be perfect on Plesk + Ngnix!