eG Monitoring
 

Measures reported by HvDynamicVHDTest

A VHD (Virtual Hard Disk) is a dynamically expanding disk on the Hyper-V server, which is initially at a few kilobytes and expands when the VMs need additional storage space. The VHDs can only grow as the VMs add data, however, to the size limit which is designated in the setup wizard. The VHDs enable administrators to create, configure, and boot physical computers without a virtual machine or hypervisor. This functionality simplifies image management because it allows to:

  • Standardize the image format and toolsets in the organization.

  • Reduce the number of images to catalog and support.

  • Enable increased server utilization to conserve energy.

If one/more VMs on the Hyper-V host utilize more dynamic memory resources (from the VHDs) than they are supposed to use, then, other VMs on the host may not have sufficient memory resources resulting in serious memory contention. To avoid memory resource contention among the VMs that use the VHDs, it is necessary to continuously track the dynamic memory allocated to the VMs from time-to-time. The HvDynamicVHDTest test helps administrators in this regard!

This test auto-discovers the VHDs of the target Microsfot Hyper-V server and reports the memory utilization of each VHD. Using this test, administrators can detect the VHD that is hogged continuously for memory resources.

Outputs of the test : One set of results for each VHD on the target Microsoft Hyper-V Server being monitored.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Total_size Indicates the total capacity of this VHD. MB  
Used_size Indicates the amount of memory that is utilized by the VMs from this VHD. MB By comparing the value of this measure across the VHDs, you will be able to identify the VHD that is being utilized at all times.

If the value of this measure is close to the Total_size measure, then, there may not beadequate memory resources for all the VMs assoicated with the VHD. This may cause performance bottlenecks in the VMs that are using the VHD.
Free_size Indicates the amount of memory that is available for use by the VMs in this VHD. MB A high value is desired for this measure.

Compare the value of this measure across the VHDs to figure out the VHD that is sparingly used.
Utilization Indicates the percentage of memory utilized on this VHD by the VMs. Percent Ideally, the value of this measure should be low.

If the value of this measure is nearing 100%, then, there may be a performance bottleneck in the VMs that are using the VHD due to memory resource contention.