Measuring whether your site is "up" or "down" seems like it would be pretty easy: Either it's available or it's not. However, effective monitoring for downtime is a bit more complicated. For example, if you can't view your site from a particular PC, how do you know your browser is not causing the problem? Since a variety of factors can all produce the same disastrous end result - downtime - you'll want to monitor accessibility from several different angles.
Understand What Your Web Host Can Tell You
If you run a typical small- to medium-size e-commerce site, chances are your site resides with a Web hosting service. Your host - an Internet service provider (ISP) - very likely provides you with statistics about your site's performance, usually via weekly reports that detail site activity. If these reports don't reflect accessibility data (a graph or chart showing the percent of time your site was up or down during the week), contact your ISP's support department and request that this metric be tracked in your reports. Be prepared to negotiate on fees for this service; the ISP field is highly competitive, so you have a great deal of bargaining power. You could easily argue that such a basic measurement should be included in your hosting package, as it is with many popular ISPs. One word of caution: getting your weekly reports to reflect downtime that may have occurred is not the same as being informed of downtime as it is occurring. For real-time notification, you will need to monitor the site yourself and/or use the services of a third party.
Learn about Tools You Can Use to Do It Yourself
The simplest way to keep a watchful eye on your site is to make it your own browser's home page. Chances are if you are unable to access your site, some of your customers are experiencing the same problem. In the unlikely event that you run your own (in-house) Web server, that server automatically generates log files. There are numerous products of varying technical complexity to help you interpret server data. A short review of these types of tools can be found in an excerpt from the bookWeb Performance Measuring Tools and Services, by Patrick Killelea.
Find Out How Third-Party Services Can Help
As high-profile e-commerce sites such as eBay and E*Trade increasingly experience crashes, the market has exploded for services that monitor site performance, particularly for those that detect and alert the company to downtime. One of the great advantages of using a site-monitoring service is that it keeps the same watchful eye on your site regardless of where your site lives: with a host or on your own server. And while many such services offer a multitude of features and are very expensive, others stick with the basics and are affordable for small businesses.