How much memory would be needed for a Wordpress site with 8.000 hits per day with the occasional spike? [duplicate]

I'm running a Wordpress site with about 8.000 hits per day, which occasionally spikes to 12.000 hits. I'm currently considering a VPS server. My setup is WP with Apache and MySQL. Can anyone recommend how much memory would be sufficient in this situation?

No one can completely answer your question without knowing details about your install, such as what plugins you are running and the memory requirements of each plugin.

Wordpress does not scale well without some sort of Caching plugin. W3 Total Cache and WP Super Cache are both great plugins that will let your site scale much beyond a default Wordpress install. These plugins essentially minimize the dynamic PHP compilation and SQL hits and instead serve HTML files.

It then becomes a calculation much like any other busy web server. How many images are coming off of your server? Is output gzipped? Are you planning for future growth? Many factors go into how fast the website will serve up and how much RAM you will need.

That being said, at your current size I think I would go with at least 1GB of RAM, assuming you use a caching plugin and have minimal graphics serving off of your server. However there are big caveats above.

I run a site that has similar numbers but also an enormous database with >50k posts and as many comments. We also run some expensive taxonomy queries on most screens so it works our database pretty hard. Without tuning we'd be totally screwed, but as it is we have a dedicated webserver using 8gb of ram and a database server with 4gb.

I know we could optimize further, and if your content isn't as huge a lot less memory is needed. I would recommend starting with at least 2gb if not 4 if you want to be able to grow your traffic further. Extra ram also lets you tweak your Apache/MySQL configurations more freely, so you can optimize load times better than if you have just enough ram to get by.