An administrator decreases the CPU share value for two virtual machines in a DRS cluster from 1000 to 100 shares. The DRS cluster contains more resources than both virtual machines can consume.
The characteristics of the virtual machines are listed below:
• The second virtual machine is a clone of the first virtual machine.
• Both virtual machines are identical in every way.
• Both virtual machines are not attached to the IP network.
• Both virtual machines are powered on.
What impact on the virtual machines’ performance will be observed?
A. The virtual machines will have equal performance under all conditions.
B. The performance of the virtual machines will reduce by a factor of ten once the share value is adjusted.
C. The virtual machines will have equal performance under normal conditions and reduced performance when contention occurs.
D. The original virtual machine will perform better than the clone when contention occurs.
Correct Answer: A
Explanation/Reference:
Explanation:
Shares specify the relative importance of a virtual machine (or resource pool). If a virtual machine has twice as many shares of a resource as another virtual machine, it is entitled to consume twice as much of that resource when these two virtual machines are competing for resources.
Shares are typically specified as High, Normal, or Low and these values specify share values with a 4:2:1 ratio, respectively. You can also select Custom to assign a specific number of shares (which expresses a proportional weight) to each virtual machine.
In this question, the two VMs CPU share value is reduced to 100. This means that the two VMs still have the same (equal) CPU share value. Therefore, the VMs will have equal CPU performance under all conditions.
Incorrect Answers:
B: The performance of the virtual machines will not reduce by a factor of ten. The question states that the DRS cluster contains more resources than both virtual machines can consume. Therefore, there is no contention. The performance of the virtual machines would reduce if there was contention. However, the only way their performance would reduce by a factor of ten is if other VMs in the cluster have ten times more shares than the two VMs in question. Therefore, this answer is incorrect.
C: The virtual machines will have equal performance under normal conditions and reduced performance when contention occurs. However, when contention occurs, the performance of the two VMs will be equally reduced so their performance will still be equal. Therefore, this answer is incorrect.
D: The original virtual machine will not perform better than the clone when contention occurs. The performance of both VMs will be equally reduced. Therefore, this answer is incorrect.
References:
https://pubs.vmware.com/vsphere-4-esx-vcenter/index.jsp?topic=/com.vmware.vsphere.resourcemanagement.doc_41/getting_started_with_resource_management/c_shares.html