VPS Resources

Domain limits

Questions: How many domains can I put on one VPS server?

The number of domains that can be hosted greatly depends on the type of work the server has to do for your application (ie website). For example if we break down the usage into processes we can easily see how the answer to this question depends on many factors, however most times optimizations can greatly increase the capabilities of a VPS without requiring upgrades.

Typical server resources include:

• CPU
• RAM
• Disk I/O
• Bandwidth

Typical services used:

• Web Server (Apache or IIS)
• DB Server (MySQL or MSSQL)
• Mail Server (Exim or SmarterMail)
• Application Server (ColdFusion, Railo, PHP)

Each service will use a combination of the resources and services to "serve" the application to the internet. The optimal configuration would utilize as much caching (database results) and optimized static files (txt, html, css, images). In addition limiting the number of outbound calls to external resources for generating site content is important. The difference between a site utilizing caching, optimized files and scheduled import of exernal resources may be from 10 to 100% better performance.

The key is optimization, a site fully optimized would likely run into a bandwidth limit before server resource usage would ever be an issue. See the examples below of bandwidth limitation for 3mbps sustained traffic, while VPS servers allow "bursting" which is periodic spikes:

1. Google (search results page) approx 2KB, can serve 11,250 results in one minute @ 3mbps or 37,500 new visitors @ 10mbps (burst).
2. Yahoo (home page results) approx 200KB, can serve 112.5 new visitors in one minute @3mbps or 375 new visitors @ 10mbps (burst).

The key to serving you can see from the example above is optimizing content. A media rich website is going to utlize many more resources both bandwidth and other thus it will handle much less than a mostly text based website.

Checklist for optimizing applications for maximum server performance:

1. Are the images on my website optimized?
2. Is an Expires or a Cache-Control Header being utilized?
3. Are all possible queries being cached in memory?
4. Are the tables being used in queries with the "where" clause indexed?
5. Are CSS, JS and other TXT resources compressed using server side (Gzip) compression?
6. Are JavaScript and CSS Minified?
7. Are the number of HTTP requests visitors have to make minimized?