Server Architecture for eZ Publish Hosting

The diagram below shows the results from our testing. The results show that eZ Publish scales almost linearly in a clustered environment. The difference between a single server and a cluster consisting of one database server and one webserver is minimal, but would nevertheless be noticeable under load.

Clustering performance chart

Interpreting the results

These test results show the number of pages served per second for several hardware scenarios. The numbers are the absolute maximum that the server can process. Therefore, to estimate performance in real-life scenarios, we need to make some calculated assumptions.

The information that is important for doing a performance estimate includes publishing frequency and the percentage of pages served cached versus un-cached. If we take the scenario with a single server and assume that 50% of the pages are served cached and 50% un-cached, we end up with a number: 19.23 pages / second (p / s).

Normally the publishing frequency of an eZ Publish site is much lower than the load that we tested (3-5 articles per second). Even very heavily loaded sites with active forums publish messages more like every minute or every 5 minutes. But if we take the numbers under extreme heavy load we get an average of 11.17 p / s. We can therefore assume that the actual number is somewhere between 11 and 19 p / s. Therefore, we will use 15 p / s as our estimated load that reflects realistic heavy usage.

15 p / s over a period of 24 hours is 1 269 000 pageviews per day. This number assumes that the server is running at peak capacity for 24 hours, instead of the normal pattern of peak capacity only during specific periods. For example, if a site is primarily used regionally during business hours, the site is probably only under load during 8 hours of the day. For such a scenario, we would estimate 432 000 pageviews per day (that is, one-third of 1 269 000). This translates to 12.96 million pageviews per month on a single server.

If we apply the same estimates to a configuration of four servers, we end up with 70 pages per second, a total of 2 million page views per day and 60.5 million pageviews per month. (These performance numbers are probably lower than what would be seen on a real site, as a site with heavy traffic would normally serve more cached pages than a low-traffic site.) In both situations we calculated with 50% of the pages dynamically generated.

These assumptions and estimates are, of course, theoretical. To get accurate statistics, you must test your own installation. In addition to hardware and eZ Publish software variations, other system activities (such as background jobs, backups, statistics systems and other processes) can add load to the server that affects performance.