[Orca-users] Re: plot difference between the actuel and the previous data of the same columns

Blair Zajac blair at akamai.com
Wed Feb 21 13:57:45 PST 2001

You can specify the data_type to be derive or counter in the
configuration file.  This will calculate a derivative of the data.
There are four different types of ways you can treat the data
in a particular column.

>From Orca's manual page, which I recommend reading once through :)

Data Source Optional Plot Options

The following options are plot optional. Like the data option, multiple
copies of these may be specified. The first option of a particular type
sets the option for the first data option, the second option refers to
the second data option, etc.

data_type *type*
  When defining data types, Orca uses the same data types as provided
  by RRD. These are (a direct quote from the RRDcreate manual page):

      is for things like temperatures or number of people in a room or
      value of a RedHat share.

      is for continuous incrementing counters like the InOctets
      counter in a router. The COUNTER data source assumes that the
      counter never decreases, except when a counter overflows. The
      update function takes the overflow into account. The counter is
      stored as a per-second rate. When the counter overflows, RRDtool
      checks if the overflow happened at the 32bit or 64bit border and
      acts accordingly by adding an appropriate value to the result.

      will store the the derivative of the line going from the last to
      the current value of the data source. This can be useful for
      gauges, for example, to measure the rate of people entering or
      leaving a room. Internally, derive works exactly like COUNTER
      but without overflow checks. So if your counter does not reset
      at 32 or 64 bit you might want to use DERIVE and combine it with
      a MIN value of 0.

      is for counters which get reset upon reading. This is used for
      fast counters which tend to overflow. So instead of reading them
      normally you reset them after every read to make sure you have a
      maximal time available before the next overflow.

  If the data_type is not specified for a data option, it defaults to


> Mbh wrote:
> Is 't possible to plot not a difference between 2 columns but between
> the actuel and the previous data of the same columns?
> Regards
> Mehdi Ben Hassen
> Network Engineer
> Altran Europe: http://www.altran-group.com
> Tel: +32 (0)3 450 36 13
> Gsm: 0476/ 76.95.82
> Email: mehdi.ben_hassen at alcatel.be
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