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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">It’s a circular buffer.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">When the buffer is filled up the oldest stuff in it is overwritten with new stuff.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">You setup the circular buffers for your needs.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Typically you want high resolution data only for items in the recent past and lower resolution data for times previous… so you setup your buffers that way.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If you want the highest resolution data for every unit of time from now until eternity you probably should look for another solution…<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">General circular buffer:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><a href="http://en.wikipedia.org/wiki/Circular_buffer">http://en.wikipedia.org/wiki/Circular_buffer</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">quick overview of RRD as a concept<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">http://en.wikipedia.org/wiki/RRDtool<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> rrd-users-bounces+dshriver=mitre.org@lists.oetiker.ch [mailto:rrd-users-bounces+dshriver=mitre.org@lists.oetiker.ch]
<b>On Behalf Of </b>Kaushal Shriyan<br>
<b>Sent:</b> Wednesday, October 02, 2013 1:24 PM<br>
<b>To:</b> rrd-users@lists.oetiker.ch<br>
<b>Subject:</b> [rrd-users] Overwrites existing data<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Hi,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">As per the URL <a href="http://oss.oetiker.ch/rrdtool/tut/rrd-beginners.en.html">
http://oss.oetiker.ch/rrdtool/tut/rrd-beginners.en.html</a> I am not sure i understand about <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">In case of linear databases, new data gets appended at the bottom of the database table. Thus its size keeps on increasing, whereas the size of an RRDtool database is determined at creation time. Imagine an RRDtool
database as the perimeter of a circle. Data is added along the perimeter. When new data reaches the starting point, it
<b>overwrites existing data.</b> This way, the size of an RRDtool database always remains constant. The name "Round Robin" stems from this behavior. <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">"When new data reaches the starting point, it overwrites existing data" Does it mean the existing data is lost? so how do i keep track of the historical data if it overwrites?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Please help me understand with examples.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Regards,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Kaushal<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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