eG Monitoring
 

Measures reported by VCVRAMUsageTest

When VMware released vSphere 5 they also implemented a new licensing model that is based on the amount of virtual RAM (vRAM) that is assigned to virtual machines. vRAM is defined as the memory configured to a virtual machine. vSphere 5 licenses are still sold by the CPU socket, but each license comes with a set vRAM entitlement that varies based on the vSphere 5 edition as shown below:

  • vSphere Standard – 32GB per CPU socket

  • vSphere Enterprise – 64GB per CPU socket

  • vSphere Enterprise Plus – 96GB per CPU socket

If the vRAM license entitlement is exceeded you must purchase another full CPU socket license to increase it. In vSphere 5, there are no limits on the amount of physical memory a host can have; instead, the limits are applied to the amount of vRAM assigned to powered on VMs. VMs that are powered off do not count against the allotment but VMs that are powered on have the full vRAM that is assigned to a VM counted towards the allotment regardless of the amount of vRAM that a guest OS is actually using. This includes all memory used by a VM, both physical host memory and any memory that a VM may be swapping to disk because of memory over-commitment.

This licensing change in vSphere 5 requires that administrators continually micro-manage their vSphere environment by controlling VM sprawl and by enforcing prudent, calculated usage of the memory resources. This test enables these administrators to better manage the vRAM and the vSphere 5 licenses by periodically reporting the vRAM allocation to VMs and their usage.

Note:

This test is applicable to vCenter 5 only.

Outputs of the test : One set of results the vCenter server being monitored.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Vram_entitled Indicates the amount of vRAM capacity currently available in the license. GB The vRAM entitlements of VMware vSphere processor licenses are pooled—that is, aggregated—across all CPU licenses managed by a VMware vCenter instance (or multiple linked VMware vCenter instances) to form a total available vRAM capacity.
Vms_poweredon Indicates the number of VMs that are currently powered on. Number  
Vram_used Indicates the amount of vRAM currently utilized by the powered-on VMs. GB If the vRAM license entitlement is exceeded or exhausted - i.e., if the value of these measures grow close to the value of the Pooled vRAM capacity measure - it is an indication that you must purchase another full CPU socket license.

To minimize this financial impact, administrators now need to do a much better job of managing their vSphere environments. No longer can they afford to waste resources and over-allocate memory to virtual machines; doing so now has a financial impact. Administrators also have to be very careful that all virtual machines are right-sized and are not allocated more memory than they actually need to support their workloads. They also need to stay on top of VM lifecycles to ensure that un-needed VMs are deleted when they are no longer needed.
Vram_used_perc Indicates the percentage of total vRAM capacity that is currently utilized by the powered on VMs. Percent
Total_vms Indicates the total number of VMs using this license. Number  
Vram_conf Indicates the amount of vRAM that will be used if all the VMs are powered on. GB These metrics help administrators evaluate the vRAM and license requirement of the virtual environment. By understanding how much vRAM would be required to power on and run all VMs, administrators can determine whether or not the current vRAM (pooled) capacity would be sufficient.

If the value of these measures are equal to or higher than the Pooled vRAM capacity measure, it indicates that the total vRAM capacity is not sufficient to support all VMs when powered on. You may hence have to decide what needs to be done to ensure that the virtual environment operates at maximum capacity, but with minimal financial impact:

  • Whether to procure additional vSphere licenses, so that the aggregate vRAM capacity increases, or,

  • Whether to power on only a few VMs at a time, so that the vRAM availability is not badly impacted;
Vram_conf_perc Indicates the percentage of the pooled vRAM capacity that will be utilized if all the VMs were powered on. Percent
Total_hosts Indicates the total number of vSphere hosts that are currently using this license. Number Use the detailed diagnosis of this measure to know which vSphere/ESX hosts are currently using the license.