Confused as to why two values in this template are backwards

[stormonts]

As shown in the graph below, the "Memory Used" and "Memory Free' values are reversed based on what is shown in "top" on that server.

Untitled.png (44.02 KiB) Viewed 929 times

The debug of the graph is below with the CDEFs shown. They appear to be correct, but the numbers aren't correct. What am I missing?

cdefs.png (92.77 KiB) Viewed 929 times

[Osiris]

What is the type of the data input Method?

[stormonts]

They are using the Net-SNMP - Buffers, Net-SNMP - Cache, Net-SNMP - Free, Net-SNMP - Total "Get SNMP Data" data templates.

bsi-util-btp - Memory - Buffers bsi-util-btp SNMP Version: 2, Community: public, OID: .1.3.6.1.4.1.2021.4.14.0
RRD: /usr/local/cacti-1.2.9/rra/bsi-util-btp_mem_buffers_3410.rrd
bsi-util-btp - Memory - Cache bsi-util-btp SNMP Version: 2, Community: public, OID: .1.3.6.1.4.1.2021.4.15.0
RRD: /usr/local/cacti-1.2.9/rra/bsi-util-btp_mem_cache_3411.rrd
bsi-util-btp - Memory - Free bsi-util-btp SNMP Version: 2, Community: public, OID: .1.3.6.1.4.1.2021.4.6.0
RRD: /usr/local/cacti-1.2.9/rra/bsi-util-btp_mem_free_3412.rrd
bsi-util-btp - Memory - memTotalReal bsi-util-btp SNMP Version: 2, Community: public, OID: .1.3.6.1.4.1.2021.4.5.0
RRD: /usr/local/cacti-1.2.9/rra/bsi-util-btp_memtotalreal_3414.rrd

[Osiris]

Can you log this into GitHub?

[stormonts]

IDone (https://github.com/Cacti/cacti/issues/3329). I didn't know if it was actually a bug or if I was just doing something wrong with CDEFs.

[stormonts]

Jimmy closed the issue on Github statng it is not a bug, so I am back to square one.

His comment was:

So, this looks like a custom graph template, not written by The Cacti Group. Reviewing the Data Template, the specific OID's seem to be correct. Review the various Graph Items and ensure that they are using the CDEF "Multiply by 1024" each and that the base units of the Graph Template are also 1024. If you want the unit's to be SI (KiB, GiB), then you need to add a "Multiply by 1000" CDEF and change the base units for the Graph Template to 1000.

But that doesn't explain why the two values (memory free and memory used) seem to be backwards.

Memory free is d,c,-,1024,* Which is (MemoryTotalReal-MemFree)*1024 correct? Why would that be giving me the value of the memory used according to top on the server (and why is the "memory used" cdef giving me the total of the memory free according to top?

[camerabob]

I'm not a CDEF pro, but shouldn't there be a minus sign in that CDEF definition? Something like "d,c,-,1024,*"

[stormonts]

There is, I just failed to type it correctly in that comment (comment is updated now).

Attached is the template if anyone wants to take a look and help me figure out where my math is wrong.

[Dummy]

To me this calculation is not clear (I'm not an expert in CDEF):
Values collected:
a=mem_buffers
b=mem_cache
c=mem_free
d=memTotalReal

Is this the correct Calculation to get Memory Used?
Memory Used = c,a,b,-,+,1024,*
= (c + (a-b)) * 1024

The values on the Graph did not match with the values from "top" - Command
Top shows: 5.712.552 Free, your graph: 1,52 Current

You had checked each single value in the graph separately before starting caluculation wiht CDEF?

[stormonts]

Yes, I did check them individually. What we are trying to show is the amount of physical memory that is used which does not include buffers/cache. (top shows "Used" as the total of buff/cache + actual memory usage).

If your break down of my equation is correct, then I guess I should change it to:

a=mem_buffers
b=mem_cache
c=mem_free
d=memTotalReal

Memory Used = d,a,b,+,-,1024,*
= (d - (a+b)) * 1024

Correct?

[camerabob]

I would go with:

Memory Used = d,a,-,b,-,1024,*
= (d - a - b) * 1024

[Dummy]

Both of the last two Posts should provide the same results

Maybe it makes sense to start with one Value as Area and three values as Lines. Only a CDEF which does the calculation '* 1024'
Then compare the Current-Values with the Values shown in "top".

If these values will match do some calculation to check which formula you will need to get the desired values.
Then just define a matching CDEF.

[stormonts]

I finally figured it out, but now I have a different problem. I am using the same graph template on multiple servers, but the problem is that the values aren't coming in the same way across devices.

In the image below, you can see that the order of DEFs is MemTotalReal, then mem_buffers, then mem_cache, then mem_free.

working.png (82.77 KiB) Viewed 879 times

This is from a system that is displaying incorrectly and the order of the DEFs is mem_buffers, then mem_cache, then mem_free, then MemTotalReal

broken.png (52.47 KiB) Viewed 879 times

Shouldn't they always be uniform since the same template is in use and the servers are all running the same OS?

[TheWitness]

You may have multiple versions of the template installed. There is a Sync Template dropdown on the Graph Templates page. You should try that.

[Dummy]

Yes, agreed with Witness. I seems you are not using only one template for your servers. Maybe you selected a different Template for your second server?
If you are using two Templates and you will stay on two Templates: it might be an idea to validate the configuration of both Templates.