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Difference between Memory Used and Physical Memory

I have noticed that when i hover over the server on the home page there is small screen pop up shown where the memory used is 72%. But when i click on the server and check the details of the server i find that the Physical memory of that sever is 98%. Is physical memory and memory used different or there is some problem the way its displayed on the small pop up.

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mstraughan

Yann answered this in Memory usage charts do not match

"The "Memory" Usage and the "Physical Memory" Utilization are calculated differently by Orion NPM.

Memory:

The Memory is the sum of the memory used by the processes listed in the HOST-RESOURCES-MIB:hrSWRunPerfTable (1.3.6.1.2.1.25.5.1).

The OID used is the hrSWRunPerfMem (1.3.6.1.2.1.25.5.1.1.2).

Physical Memory:

The Physical Memory is calculated based on the values populated in the HOST-RESOURCES-MIB:hrStorageTable (1.3.6.1.2.1.25.2.2.3).

The OIDs used are hrStorageSize (1.3.6.1.2.1.25.2.3.1.5), hrStorageUsed (1.3.6.1.2.1.25.2.3.1.6) and hrStorageAllocationUnits (1.3.6.1.2.1.25.2.3.1.4) .

Depending how the SNMP agent on the host is reporting values, it can lead to some discrepancies between the two results.

I would advise you to use the most accurate between both and unmanage the other element.

Results will vary depending of the plaftorms.

I hope this helps you.

Regards,

Yann"

nemko

Hi,

Did you find the answer to your question? Apparently I have the same question. Memory used is showing around 10%. But physical memory shows around 100%. Is there any explanation?

ave cpu mem.JPG physical memory.JPG

Best,

Nemko

Deltona

There's something you need to be aware of when monitoring Linux nodes using net-SNMP. The problem lies in that net-snmp on linux, reports physical memory as being real memory usage combined with buffer and cache usage.

On almost any other system, physical memory usage returns just that: physical memory usage.

But for Linux machines, physical memory usage counter = physical memory usage + buffer + cache. This explains why you are seing a high physical memory usage when drilling down on the Node. You can confirm this by displaying memory usage directly in the Linux server.

The popup/callout displayed when pointing at the Node displays the real memory usage as gathered through the CPU & Memory poller.

When you drill down and view the cached, buffer and physical volume details, you are actually looking at the individual pollers for those types of elements.

My advice is to list resources on the net-SNMP node and uncheck cached, buffer and physical memory as a minimum, so that you only rely on the CPU & Memory poller for actual memory usage.

aLTeReGo

Note that the issue Deltona describes above is addressed when using the Linux Agent.

nemko

Okay understood.

The node I was asking about is polled with SNMP. What should I do about the issue?

Deltona

Hi nemko

Did the advice provided not make a difference?