We report a site's operating system, web server,
and netblock owner together with, if available,
a graphical view of the time since last reboot for
each of the computers serving the site. Further information about
what we measure and how we measure it is and other factors affecting
the monitoring process are available here.
The graphs for each site display both the actual times since last reboot (as an X) and
a moving average of uptime over time as a solid green area graph. The colour of the X
changes in the event of the site switching operating system.
A history of the operating system, web server and hosting location
is also provided so it is possible
to correlate these changes with the uptime of the site.
When we are unable to get a valid uptime measurement for a site, a
gap will appear in the plots of the raw data points.
Queries are made on a daily basis, so the crosses on single server site
will appear as a diagonal line moving forward through time until the next
reboot.
Sites using multiple front end
servers with some form of load
balancer will show parallel diagonal lines.
A good example is the
BBC
site.
Daily reports are generated showing the sites
and hosting locations with the longest uptimes.
Explanation:The chart shows the time since May 1999 when we first started monitoring www.apple.com
through to March 2001. Each vertical line on the X axis represents two months.
Each small 'x' on the chart represents a reading on a particular day.
In the first few months we can see two blue lines representing
the servers servicing the site. They are blue, which represents Solaris in
this example. At June 1999 it looks like there are two Solaris servers, one of
which is restarted at the beginning of June whilst the other continues to
run until the start of July 1999, when it is also restarted.
We can also see at the bottom of the graph the occasional appearance of MacOSX (in pink).
From December 1999 there are more clearly three Solaris servers running
with different uptimes. Two of them appear to be restarted at the start of
April 2000 to run with very similar uptimes. In June 2000 all three were
restarted, and the MacOSX system starts to run in parallel as the Solaris
systems are phased out, until it becomes the only operating system servicing the
site.
Explanation:This table shows the Maximum and Latest uptimes in days for each of the Operating Systems we
have detected. The No. of samples is the number of samples for each type we have recorded, usually one per day.
Explanation: From this table we can see that IP address has remained constant,
even though we are detecting several different Operating Systems at this
address. This and the graph above confirm that there is more than one
type of Operating System in use in parallel.
Explanation: Telewest is an example of site that has gone through a number of
Operating Systems and Web Servers in recent history. The chart above shows them starting
out with IRIX, then changing overnight to Linux, followed by the current HP-UX.
Note the scale of the chart, each Operating System ran for more than 50 days before being restarted. Note also the
initial value for Linux, at mid March 2000. This had been running for 60 days when the IRIX system
was switched over to the Linux one, although it was restarted a few days later before running
up to 60 days again. Simillarly the HP-UX system has been running for approximately 40 days before
it started to serve the live site.
