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ESX Server Virtual Machines CPU and Memory usage

I opened a ticket for this issue but was told to open a forum post instead because it wasn't a bug. so here goes.

we have multiple vm hosts and vm machines on those hosts. i have users who want to know how much CPU and RAM is being used in percentages. they get alerts when certain CPU thresholds are met and same with RAM. when that happens they call the server team and the technician looks in Virtual Center and says its no way close to that amount.

So basically, when i am in node view for a VM server, i see the CPU load and memory utilization gauges. they provide one type of information.

Then under the Virtual Machine Details section, it shows “memory usage of this guest” which from what I take from your Solarwinds documentation is the amount of RAM being used.

Then under the disk volume section, the “physical memory” section which shows another value for RAM used.

Which one of these is right?

All i am looking for is a point where my users can go to see what is a correct value.

Any ideas anyone??

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bshopp

Sorry for the delay and not getting you a response on this.

Under the Virtual Machine Details section, it shows "memory usage of this guest" which is the amount of RAM being used. This is the value reported to us from the ESX server. Of the RAM on the ESX server, how much RAM is actually being used by the VM from the ESX server’s perspective.

Under the disk volume section, the “physical memory” section which shows another value for RAM used, this is a value acquired from the Windows server itself. The Windows server “doesn’t know” that it is a VM. The ESX server lets it behave like a normal server. According to the Windows server it is using that much of its physical memory. That value is not calculated, but is a value returned from an SNMP query to the Windows server itself.

The memory utilization from the Windows server gives the memory utilization from the Windows server perspective – what the Windows server believes it is using of physical memory. High memory utilization here means that the Windows machine believes it is using a lot of its memory. Due to the complex nature of the ESX server, it is able to give RAM to a machine that doesn’t actually reside in the actual RAM of the physical machine. Thus, the value of the ESX server is that you can have more virtual RAM than actual physical RAM. The value from the ESX server is important as a whole. The ESX server reports all the RAM utilizations from all the VMs and should be monitored independently of the independent machines. Both values are important and should be monitored as such. When the Windows Server believes it is using a lot of RAM, then you will have performance issues. If all the VMs on your ESX server are using a lot of RAM, your ESX server and possibly the VMs on the ESX server might have performance issues. Monitor them both. Here is a useful link to understand how this technology works on the ESX server: http://vmetc.com/2009/01/30/vmware-esx-memory-over-commit-technology-explained/

kulastone

With that said, what role does the memory used gauge play in this scenario?

What OID is used when polling the "Memory usage of this guest"? it would be usefully to make that into a chart that my users can use.

Karlo.Zatylny

Hi,

The memory used gauge for a Windows server is the sum total of memory usage reported by all processes on the server. Other devices give their memory utilization via other OIDs/calculations.

The OID used for the memory usage of this guest is 1.3.6.1.4.1.6876.3.2.4.1.4.

The chart of those values is shown on the ESX server itself, with each VM having its own color in the memory chart.

Please let us know if you have any additional questions.

Thanks