Draw an area in a graph between two variables without stack.

[FredZwarts]

I started using Cacti a few weeks ago. There is something I want to do, but I cannot find how to do it. If I missed something in the documentation, I would like a pointer.
I want to create a graph for a temperature. I want a line for the average temperature and I want to color the area between the minimum and maximum temperature. In order to draw this area, I cannot stack the maximum temperature on the minimum temperature, because their values would be added for the upper boundary of the area. I assume that I first have to subtract the minimum from the maximum and than stack that difference on the minimum using AREA:STACK. But how does one perform such a subtraction?

[TheWitness]

Using a CDEF. You have to perform some light magic. To determine the DEF names as Cacti controls those, but that's what you do.

[FredZwarts]

Using a CDEF. You have to perform some light magic. To determine the DEF names as Cacti controls those, but that's what you do.

Where do I start to find those DEF names?

[FredZwarts]

Using a CDEF. You have to perform some light magic. To determine the DEF names as Cacti controls those, but that's what you do.

Where do I start to find those DEF names?

I think I found it already.

[FredZwarts]

Using a CDEF. You have to perform some light magic. To determine the DEF names as Cacti controls those, but that's what you do.

It does not work. It tried 'cdef=CURRENT_DATA_SOURCE,CURRENT_DS_MINIMUM_VALUE,-',
but then the graph shows "ERROR: don't understand 'U,-'".
I also tried 'cdef=CURRENT_DS_MAXIMUM_VALUE,CURRENT_DS_MINIMUM_VALUE,-',
but then the graph shows "ERROR: don't understand 'U,U,-'".
Without the CDEF the graph is displayed without error; the maximum is stacked on the minimum, but then the upper boundary is much too high.
Apparently the CURRENT_DS_MAXIMUM_VALUE and CURRENT_DS_MINIMUM_VALUE are incorrect, but I have no idea what it should be.

[TheWitness]

I would not use the magic, but instead vnames start with a, b, c, ... Use those instead. Look at the Advanced Ping Graph template for some clues.

[FredZwarts]

I would not use the magic, but instead vnames start with a, b, c, ... Use those instead. Look at the Advanced Ping Graph template for some clues.

Thanks! I think I have it working now.

[TheWitness]

Great.