How many visitors can my site handle?

Assuming I have excellent upstream bandwidth do you think having 5 ECU’s (CPU Units), 2 Cores, and having 1.7GB of memory will be sufficient enough to handle high load traffic? I’m really worried/optimistic that my site will do good and I want to be able to be able to tackle that problem if it happens. It’s also running on wordpress. Please tell me what you think.
Answer #1
You should be fine. Biggest bottleneck is probably disk IO, consider deploying a memcache
Answer #2
Okay phew, I just have a question, what is considers disk I/O? For example what do I have to do on my website to be charged for I/O? Uploading pictures? Also how is memory used on a server? I have wordpress, is it by uploading plugins and activating them?
Answer #3
jasonxman replied: Okay phew, I just have a question, what is considers disk I/O? For example what do I have to do on my website to be charged for I/O? Uploading pictures? Also how is memory used on a server? I have wordpress, is it by uploading plugins and activating them?
Every time one of the static resources (eg, images, CSS files, pages like the home page that dont change very often) is accessed, the web server has to read the file off the disk, and if its a PHP file, parse and execute it. This in itself isnt a very resource intensive process, but if its being done hundreds of times a second, it can add up very quickly and slow the site down. Memcache works by sitting in between the webserver software and the client. When someone requests a resource, memcache checks to see if anyone has accessed the resource recently. If they havnt, memcache forwards the request to the web server, and stores a copy of the response in memory. If they have, the saved response is sent, reducing the number of times the disk has to be accessed, and because the disk is typically the slowest part of the system, response time is decreased.
HOWEVER
Preemptive optimization is almost always a waste of time. The server you have is probably powerful enough to support a small to medium sized wordpress blog (assuming you arnt limited by bandwidth). Worry about content, and getting traffic to your site before you worry about if your server can handle the hundreds of hits a second that you dont have yet.