January 22, 2010

Is there a Difference between Uptime and Availability?

In an attempt to describe how good or reliable their product is, there are two terms used in the hosting industry. These terms are uptime and availability, and today many people (both in and out of the business) think that these two terms mean the same and are completely interchangable. When studying the reliability of a hosting company, it is important to understand that these terms are not synonymous, and this is a vital point to discuss with your hosting company.
First, what does ‘uptime’ signify? Uptime is the most common term used, and it tries to convey the impression that this is the time your website will be up and available to your clients. In reality, however, uptime generally signifies the time that the actual server is up and powered on and available to the system administrators. Having a server up and powered on does nothing for your company if the actual services that your site requires are not up. Take for example, the scenario in which the web server your site is currently on is up and running, but the Apache web service is stopped. This counts as uptime for the server and the hosting company, but your website is still down, causing you to lose business, while the hosting company gets to pad their statistics.
Instead, ‘availability’ is the term that you should be looking for. According to Dictionary.com, ‘availablilty’ means the servers are ‘present and ready for use’, ‘willing to serve or assist’ or in other words – the server is up and ALL services with it. Nerds On Site measures it’s services availability, not the uptime of our servers. Thus, our trust site (trust.nerdsisp.com) measures the amount of time ALL our SERVICES are up and running for you and your businesses.
In the past week, I had the opportunity to observe a major company publish a live 100% uptime statistic, while in fact one of their most crucial services was down. They were correct in publishing the 100% uptime statistic, since the server in question was indeed running, but since the services on that server weren’t running, no one could access it. Thus uptime was 100%, but availability for that period was 0%.
It is true that some hosting companies use the term ‘uptime’ but mean and measure ‘availability’, but the general mis-use of terms means that the discerning client would be mislead by these statistics. I encourage every business IT Manager to immediately contact their hosting company and ask them to justify their use of the two terms, and to backup their statistics.