Selecting a webserver configuration

Solution 1:

Most of the metrics you've quoted are irrelevant to predicting capacity - and there's a lot of information missing which you do need.

As long as you use a shared server, its very difficult to know exactly how much CPU you do have available - if you've outgrown your VPS then a dedicated machnie is probably the way to go.

You haven't mentioned what webserver/OS you are currently using nor whether you currently use SSL.

I think some of the requests serving might be slow, because I see high bounce rate

Think? You really need to start measuring this. What do you mean by 'bounce rate'?

First thing to do is to start measuring how your site is behaving - start recording %D in your logs and if you're using mysql, set a low threshold for the slow query log.

Next, make sure you're site is well configured for performance - install an opcode cache, make sure you're serving up good caching instructions, enable compression (for PHP you need the gzhandler).

You're a very long way from needing 100MBps capacity - but it makes sense to go for this speed on your network card for other reasons.

Start recording the number of httpd processes you've got running and compare this with the available memory (less buffers and caches) reported by 'free'. Depending on the spread of usage, and with a very small database, you should aim to have enough free memory to accomodate 80% of your static content and database files.