Module 9: Resource Monitoring Lesson 2: Virtual CPU and Memory Concepts Flashcards
(23 cards)
How many virtual CPUs (vCPUs) can be configured on a virtual machine?
8 vCPUs
The VMkernel includes a ______ ______ that ______ schedules vCPUs on the physical processor of the host system.
The VMkernel includes a CPU scheduler that dynamically schedules vCPUs on the physical processor of the host system.
What is a CPU socket?
A single integrated socket
What is a processor core?
A logical processor, two or more can be held within a single CPU socket
How does ESX/ESXi utilize hyperthreading?
ESX/ESXi can execute two threads, or sets of instructions, at the same time
How do you access the hyperthreading option in the vSphere Client?
Hosts configuration tab, select processors, click properties
How often does the VMkernel look to migrate vCPUs from one logical processor to another to keep the load balanced?
Every 2-40 milliseconds
For ESX hosts, what CPU does the service console run on?
The first logical processor
What happens if a logical processor has no work?
It is put into a halted state
On an ESX host, how much memory does the service console typically use?
300MB
What does virtualization memory overhead size depend on?
The total memory size and number of vCPUs
What feature helps with memory overcommitment and performance?
Memory compression
What happens to pages that can be compressed to a KB or smaller?
It is stored in the virtual machine’s compression cache
What is transparent page sharing?
A feature that dynamically scans memory for duplicate pages
How does transparent page sharing work?
Memory pages with identical content are arranged to be shared
What happens when a virtual machine attempts to modify a memory page that is shared?
The VMkernel creates a new, private copy for that virtual machine. Other virtual machines continue to share the original page
In what scenario would transparent page sharing not be beneficial?
If you plan to suspend and resume large batches of virtual machines. Virtual machines do not immediately participate in memory page sharing
What does the term “balloon driver” refer to?
The vmmemctl device driver
Where and when is the balloon driver installed?
It is installed on the guest operating system when VMware Tools is installed
What is the function of the balloon driver?
To demand or relinquish memory from the guest operating system under control of the VMkernel
What is the VMkernel swap file?
A backing store for the virtual machine’s RAM
What happens to the VMkernel swap file of a virtual machine when it is turned off?
It gets deleted
What percentage of memory can be taken away in the ballooning process?
Up to 65%
