Why would a vSphere administrator configure resource shares for a virtual machine?
A. To prioritize access to a resource during contention
B. To guarantee access to a resource during contention
C. To prioritize access to a resource at all times
D. To guarantee access to a resource at all times
Correct Answer: A
Explanation/Reference:
Explanation:
Configuring resource shares helps an administrator to accomplish the following:
Performance Isolation - prevent virtual machines from monopolizing resources and guarantee predictable service rates.
Efficient Utilization - exploit undercommitted resources and overcommit with graceful degradation.
Easy Administration - control the relative importance of virtual machines, provide flexible dynamic partitioning, and meet absolute service-level agreements.
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.
Incorrect Answers:
B: Resource Shares does not guarantee access to resources during contention; it prioritizes access. Resource Reservations guarantee access to resources.
C: Resource Shares prioritizes access during contention, that is, when more than one VM competes for a resource.
D: Resource Shares does not guarantee access to resources, it prioritizes access during contention, that is, when more than one VM competes for a resource. Resource Reservations guarantee access to resources.
References:
http://pubs.vmware.com/vsphere-55/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-55-resource-management-guide.pdf Page 12
Liebowitz, Matt, Christopher Kusek and Rynardt Spies, VMware vSphere Performance: Designing CPU, Memory, Storage, and Networking for Performance-Intensive Workloads, Sybex, Indianapolis, 2014, pp 87-88, 118
