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Tutorial: Uptime

Discussion in 'Web Hosting' started by Dr_Michael, Jan 30, 2013.

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  1. #1
    UPTIME

    What Uptime stands for?
    Uptime is a measure of the time a server has been running without any downtime.

    Why it is counted in percentage?
    Usually hosting companies mention their server’s uptime in percentage such as 99,9% or 99,99% and so on. This is automatically calculated according the downtime per specific time period. On the above table you can see some examples:

    Availability % Downtime per year Downtime per month
    99% 3.65 days 7.20 hours
    99.5% 1.83 days 3.60 hours
    99.8% 17.52 hours 86.23 minutes
    99.9% 8.76 hours 43.8 minutes
    99.95% 4.38 hours 21.56 minutes
    99.99% 52.56 minutes 4.32 minutes

    Is there uptime of 100%?
    No, there is no server being available for 365 days per year. Even if you can find uptime of 100% in one month period, it will be hard to find uptime of 100% during a year or forever. Servers even if they do not have failures, they need updates and restarts, which result in some minutes of downtime thus the percentage cannot be 100%.

    Is 99.99% the same with 99.9%?
    No! 99.9% is the same with 99.90%. As you can see on the table, in one month period 99.9% uptime means almost 9 hours of downtime, while 99.99% uptime means almost 1 hour of downtime. So be careful on reading the numbers.

    Should I go with a hosting company that promise 99.9% uptime?
    If they guarantee 99.9% uptime, it means they may offer even better uptime such as 99.97%. The number can vary from 99.90% up to 99.99%. So, before registering with them, ask for uptime charts.

    Are there third-party uptime checkers?
    Yes there are many uptime checkers such as:
    www.pingdom.com
    http://www.webhostingstuff.com/
    www.site-uptime.net
    and so on.

    So take this advice: Before choosing a web hosting company, be sure to ask for the uptime history charts from third-parties for the specific server that they are going to host your sites. Check the table and then you can decide if their downtime is affordable for your requirements.

    Source:
    http://en.wikipedia.org/wiki/High_availability

    An example of uptime calculator:
    http://easyuptimecalc.com/index.php
     
    Dr_Michael, Jan 30, 2013 IP