<html><body><div>The documentation is not specific.</div><div><br></div><div>What are the time sub new and time sub old in the formula below?</div><div><br></div><div>Are those the wakeup times of the current and immediate prior collectd data point?</div><div><br></div><div>If so, or if not, how do I find out what they are?</div><div><br></div><div>Thanks!</div><div><br></div><div>Stuart</div><div><br></div><div><font face="Times New Roman">
</font><p style="margin: 0in 0in 0pt;"><a href="https://collectd.org/wiki/index.php/Data_source"><font color="#0000ff" face="Calibri">https://collectd.org/wiki/index.php/Data_source</font></a></p><font face="Times New Roman">
</font><p style="margin: 0in 0in 0pt;"><font face="Calibri"> </font></p><font face="Times New Roman">
</font><p style="background: rgb(246, 246, 246); margin: 0in 0in 0pt;"><code><b><span style="padding: 0in; border: 1pt windowtext; border-image: none; color: rgb(173, 76, 33); font-size: 10pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-border-alt: none windowtext 0in;">GAUGE</span></b></code></p><font face="Times New Roman">
</font><p style="background: rgb(246, 246, 246); margin: 0in 0in 0pt 0.5in;"><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'>A<span> </span></span><code style="color: inherit;"><span style="padding: 0in; border: 1pt windowtext; border-image: none; color: black; font-size: 10pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-border-alt: none windowtext 0in;">GAUGE</span></code><span><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'> </span></span><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'>value is
simply stored as-is. This is the right choice for values which may increase as
well as decrease, such as temperatures or the amount of memory used.</span></p><font face="Times New Roman">
</font><p style="background: rgb(246, 246, 246); margin: 0in 0in 0pt 11.25pt;"><code style="color: inherit;"><b><span style="padding: 0in; border: 1pt windowtext; border-image: none; color: rgb(173, 76, 33); font-size: 10pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-border-alt: none windowtext 0in;">DERIVE</span></b></code></p><font face="Times New Roman">
</font><p style="background: rgb(246, 246, 246); margin: 0in 0in 0pt 0.5in;"><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'>These data
sources assume that the<span> </span><i>change</i><span> </span>of the value is interesting, i.e. the<span> </span><i>derivative</i>. Such data sources
are very common with events that can be counted, for example the number of
emails that have been received by an MTA since it was started. The total number
of emails is not interesting, but the<span> </span><i>change</i><span> </span>since the value has been read the last
time. The value is therefore converted to a<span> </span><i>rate</i><span> </span>using the following formula (see:<span> </span><a title="http://en.wikipedia.org/wiki/Finite_difference" style="background-position: 0% 50%;" href="http://en.wikipedia.org/wiki/Finite_difference"><span style="padding: 0in; border: 1pt windowtext; border-image: none; color: rgb(14, 109, 157); mso-border-alt: none windowtext 0in;">Finite difference (Wikipedia)</span></a>):</span></p><font face="Times New Roman">
</font><p style="background: rgb(246, 246, 246); margin: 0in 0in 0pt 0.5in;"><span style="color: black; font-size: 9pt; mso-no-proof: yes;"><font face="Times New Roman"><img width="222" height="47" alt="\textit{rate} = \frac{\textit{value}_\mathrm{new} - \textit{value}_\mathrm{old}}{\textit{time}_\mathrm{new} - \textit{time}_\mathrm{old}}" src="data:image/png;base64,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" border="0" v:shapes="Picture_x0020_1"></font></span></p><font face="Times New Roman">
</font><p style="background: rgb(246, 246, 246); margin: 0in 0in 0pt 0.5in;"><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'>Please
note that if<span> </span></span><font face="Calibri"><i><span style="color: black; font-size: 9pt;">value</span></i><sub><span style="color: black; font-size: 9pt;">new</span></sub><span style="color: black; font-size: 9pt;"> </span><span style="color: black; font-size: 9pt;"><</span><span style="color: black; font-size: 9pt;"> </span><i><span style="color: black; font-size: 9pt;">value</span></i><sub><span style="color: black; font-size: 9pt;">old</span></sub></font><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'>, the
resulting<span> </span><i>rate</i><span> </span>will be negative. If you set the<span> </span><i>minimum</i><span> </span>value to zero, such data points will
be discarded. Using<span> </span></span><code style="color: inherit;"><span style="padding: 0in; border: 1pt windowtext; border-image: none; color: black; font-size: 10pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-border-alt: none windowtext 0in;">DERIVE</span></code><span><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'> </span></span><span style='color: black; font-family: "Arial","sans-serif"; font-size: 9pt;'>data sources and a minimum value of zero is recommended for
counters that rarely overflow, i.e. wrap-around after their maximum value has
been reached. This data source type is available since<span> </span><a title="Version 4.8" style="background-position: 0% 50%;" href="https://collectd.org/wiki/index.php/Version_4.8"><span style="padding: 0in; border: 1pt windowtext; border-image: none; color: rgb(14, 109, 157); mso-border-alt: none windowtext 0in;">version 4.8</span></a>.</span></p><font face="Times New Roman">
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