4.8. MultiCheck graphs

Presenting the results from multiple checks in a single graph can provide insights into how different checks interact or simply provide a more detailed view of the current status on a monitored device or system. MultiChecks provide a way of configuring a view of multiple existing checks in a single graph.

You can add a MultiCheck anywhere where you can have checks; under NetChecks, AgentChecks or SnmpChecks. Simply go to Configure under a node, and select Add MultiCheck.

In the example image here, we can see that there already is a multicheck named "Temperatures" right above the Add MultiCheck option.

After clicking the Add MultiCheck button, a name for the MultiCheck must be specified. Pick any short and descriptive name that would fit the MultiCheck you wish to create. In this example, we name it Load response, because we wish to display the response time of the server against the load of the server, to see if the response time is affected noticeably by the load of the server.

Once the empty MultiCheck has been named, it is now possible to add either single series or sums of a set of series to the MultiCheck.

In order to create a MultiCheck with the load of the server and the response time of the server, we simply click Add curve representing a single check once to add the load and once to add the IMAP check. For each check or "series" that is added, one must choose a descriptive name for this series. The name defaults to the check name of the series, but it many cases it can be desirable to insert a shorter name instead.

One can add any number of checks to a MultiCheck. However, it is rarely practical to add more than 4-8 checks, because the resulting graphs become increasingly difficult to interpret. Another thing one should consider, is the unit of the included checks. The graph routines in SysOrb will add more axes to the graph to accommodate one unit per axis. If one adds many checks with different units, the graph will become much more difficult to read for most users, as graphs with more than two or three axes are not commonly used elsewhere.

Once the series we want in the MultiCheck have been added, the check configuration should look something like the image below.

In the example, we have added two existing checks to the MultiCheck; the IMAP response time (a NetCheck) and the UN*X load average (an AgentCheck).

Clicking Overview to the left will take us from Configure mode to Overview mode, and will show us the MultiCheck. Take a look at the example image below, and read on for the explanation of the graph.

The blue box left of IMAP response tells us that this series is associated with the left-side axis. Correspondingly, the blue box to the right of the Load line tells us that the load average series is associated with the right-side axis.

Looking at the right-side and left-side axes, it is also clear why the two checks are associated with each their axis. The left-side axis (response time) represents 0 to 40 ms, while the right-side axis (load) represents a (unit-less) load average from 0 to 1.

The above begs the question; what happens with the axes as we add more series? In that case, SysOrb attempts to do the most sensible thing; it will collect all series which use identical units on the same axis. And it will add axes as needed, to accommodate every unit used. The end result will be a graph with as few axes as possible. In the example below, we have added SMTP response (which is measured in ms just like the IMAP response), and processor temperature (which is measured in Degrees Celsius, which will be the 3rd unit we add to the graph).

On the above graph, we can see (from the blue box left of the first line) that the CPU Temperature is displayed on the left axis. The second and third lines (IMAP and SMTP response times) both have their boxes over the first of the right-side axes, thus telling us that since they are both measured in ms, their values can be read out on that 0 to 100 ms axis. The fourth series, the load, is shown on the right-most axis, as is evident by the blue box to the right of the fourth line, above the right-most series.