[rrd-users] xport values and Cricket logs don't match up

[Goldblatt, Eric]

Hi,

My organization uses Cricket to collect inOctets and outOctets on
routers. We store the data in rrdtool.

Our Cricket/rrdtool administrator sent me an excerpt of a Cricket log,
along with the corresponding result from the rrdtool xport utility. I
can't get the values to match up, even when I interpolate the deltas for
the timestamps.

We are collecting every 15 minutes (900 seconds), with a heartbeat of 30
minutes.

Here is the Cricket log. The times are Eastern Standard Time (GMT-5).
The first number is inOctets.

[27-Nov-2006 05:49:05 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2228976520,1821256617
[27-Nov-2006 06:04:07 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2229497006,1822226710
[27-Nov-2006 06:19:05 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2230019486,1822966849
[27-Nov-2006 06:34:06 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2230394323,1823437686
[27-Nov-2006 06:49:06 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2230881296,1824154422
[27-Nov-2006 07:04:07 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2231325195,1824728302
[27-Nov-2006 07:19:07 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2231834304,1825463491
[27-Nov-2006 07:34:06 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2232302922,1826253282
[27-Nov-2006 07:49:07 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2233037721,1826981974
[27-Nov-2006 08:04:08 ] Retrieved data for ssa-showlo-az-n83c1_se0-0_if
(1): 2233698468,1827980243

Here is the result of rrdtool xport for the same interface. The first
value is InBytesPerSecond.

<xport>
  <meta>
    <start>1164604500</start>
    <step>900</step>
    <end>1164690000</end>
    <rows>96</rows>
    <columns>2</columns>
    <legend>
      <entry></entry>
      <entry></entry>
    </legend>
  </meta>
  <data>
    ....	
 
<row><t>1164624300</t><v>5.8682873218e+02</v><v>6.6779074378e+02</v></ro
w>
 
<row><t>1164625200</t><v>5.8599484280e+02</v><v>9.4115757996e+02</v></ro
w>
 
<row><t>1164626100</t><v>5.8036120522e+02</v><v>8.9300100143e+02</v></ro
w>
 
<row><t>1164627000</t><v>4.6121499652e+02</v><v>6.0479401611e+02</v></ro
w>
 
<row><t>1164627900</t><v>5.0687749074e+02</v><v>7.2146234864e+02</v></ro
w>
 
<row><t>1164628800</t><v>5.0604922048e+02</v><v>6.8074001731e+02</v></ro
w>
 
<row><t>1164629700</t><v>5.4554124742e+02</v><v>7.6733857827e+02</v></ro
w>
 
<row><t>1164630600</t><v>5.3314918736e+02</v><v>8.6104955942e+02</v></ro
w>
 
<row><t>1164631500</t><v>7.3489891666e+02</v><v>8.2795177527e+02</v></ro
w>
 
<row><t>1164632400</t><v>7.5641274117e+02</v><v>1.0262607498e+03</v></ro
w>
    ....
  </data>
</xport>


When I convert the server times (Eastern Standard Time) to unix
timestamps, take the differences of the inOctets counters from the
Cricket log, and divide by 900 to get bytes per second, I get the
following:

Date	Time (E.S.T.) RoundedTime(EST) UnixTimestamp
CricketLogInBytesPerSec	RRDxportInBytesPerSec	   
27-Nov-06	5:49:05	5:45:00 AM	1164624300

27-Nov-06	6:04:07	6:00:00 AM	1164625200	5.7831777778E+02
5.8599484280E+02	   
27-Nov-06	6:19:05	6:15:00 AM	1164626100	5.8053333333E+02
5.8036120522E+02	   
27-Nov-06	6:34:06	6:30:00 AM	1164627000	4.1648555556E+02
4.6121499652E+02	   
27-Nov-06	6:49:06	6:45:00 AM	1164627900	5.4108111111E+02
5.0687749074E+02	   
27-Nov-06	7:04:07	7:00:00 AM	1164628800	4.9322111111E+02
5.0604922048E+02	   
27-Nov-06	7:19:07	7:15:00 AM	1164629700	5.6567666667E+02
5.4554124742E+02	   
27-Nov-06	7:34:06	7:30:00 AM	1164630600	5.2068666667E+02
5.3314918736E+02	   
27-Nov-06	7:49:07	7:45:00 AM	1164631500	8.1644333333E+02
7.3489891666E+02	   
27-Nov-06	8:04:08	8:00:00 AM	1164632400	7.3416333333E+02
7.5641274117E+02

I expected the values in the last two columns to agree almost exactly.
What am I doing wrong?


Eric Goldblatt
Social Security Administration

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