A vSphere administrator needs the ability to adjust the amount of guaranteed physical CPU and Memory resources to a virtual machine without incurring application downtime.
Which actions must the administrator perform?
A. Enable CPU hotplug and Memory hotplug on the virtual machine.
B. Adjust the number of CPUs and the Memory Configuration for the virtual machine.
C. Adjust the CPU reservation slider and click the Reserve all Guest Memory checkbox.
D. Adjust the CPU and Memory reservation sliders on the virtual machine.
Correct Answer: D
Explanation/Reference:
Explanation:
A reservation specifies the guaranteed minimum allocation for a virtual machine. vCenter Server or ESXi allows you to power on a virtual machine only if there are enough unreserved resources to satisfy the reservation of the virtual machine. The server guarantees that amount even when the physical server is heavily loaded. The reservation is expressed in concrete units (megahertz or megabytes).
For example, assume you have 2GHz available and specify a reservation of 1GHz for VM1 and 1GHz for VM2. Now each virtual machine is guaranteed to get 1GHz if it needs it. However, if VM1 is using only 500MHz, VM2 can use 1.5GHz.
Reservation defaults to 0. You can specify a reservation if you need to guarantee that the minimum required amounts of CPU or memory are always available for the virtual machine.
You can adjust the reservation for CPU or memory by moving the slider on the Resources tab in the VM’s properties.
Incorrect Answers:
A: CPU hotplug and Memory hotplug enable you to increase the number of CPUs or amount of memory while the VM is running. However, this does not guarantee that the host resources are available to the VM. A reservation does guarantee that the resources are ‘reserved’ for the VM.
B: You cannot adjust the number of CPUs and the Memory Configuration for the virtual machine unless CPU hotplug and Memory hotplug are enabled. However, this does not guarantee that the host resources are available to the VM. A reservation does guarantee that the resources are ‘reserved’ for the VM.
C: With the ‘Reserve all guest memory’ box checked, the memory reservation is immediately readjusted when the memory configuration changes. Increase the memory size and the memory reservation is automatically increased as well. Reduce the memory size of a virtual machine, and the reservation is immediately reduced. However, you can only change the memory configuration if Memory hotplug is enabled.
References:
http://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vsphere.resmgmt.doc_50%2FGUID-8B88D3D8-E9D9-4C05-A065-B3DE1FFFB401.html