# [rrd-users] Re: Question on update

Thomas Erskine thomas.erskine at sympatico.ca
Thu Sep 18 18:41:57 MEST 2003

```At 12:19 2003-09-18, Logg, Connie A. wrote:
>Please clarify for me.  Hummm...my bins are 10 minutes wide on the 10
minutes.
>
>If I bin a value 1000 at 10:35, the value displayed on that graph is 1000
>for the 10 minute bin...correct?

No.  Say you give it 1000 at 10:35 and 2000 at 10:45.  It wants to store a
value at 10:40, so you'll probably end up with a value of 1500 at
10:40.  You're not giving it a value for a bin, you're giving it a value at
a particular instant.  From that it interpolates to figure out what the
value would have been at the correct update time.  It's very fussy about
getting the updates exactly when they're supposed to come.  If you throw
them in whenever, don't expect to be able to get back anything except
approximations of what you put in.

>Now suppose I add another value (2000) at 10:37. What will be the value for
>that 10 minute bin? 3000?
>
>I am sure that there is something simple I am missing here.
>
>Connie
>
>-----Original Message-----
>From: Leigh Sharpe [mailto:lsharpe at pacificwireless.com.au]
>Sent: Wednesday, September 17, 2003 8:49 PM
>To: Logg, Connie A.; rrd-users at list.ee.ethz.ch
>Subject: Re: [rrd-users] Question on update
>
>
>Neither.
>RRDtool calculates the value at ,say, 10:60 based on the values it got at
>10:50, 10:59 and 10:70.
>
>----- Original Message -----
>
>> I have an rrd defined for 10 minute intervals.  Sometime I have data
>> at
>say 10:50, 10:59, 10:60, 10:70
>>
>> What happens when I call update each time? In particular, does the
>> 10:59
>value clobber the 10:50 value, or are they added together?
>
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Thomas Erskine <thomas.erskine at sympatico.ca> +1.613.591.8490

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