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Virtual Machines Flashcards

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1
Q

What is the fundamental idea of Virtual Machines?

A

Abstract hardware of a single computer into several different execution environments

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2
Q

What are the components of a Virtual Machine?

A
  • Host - underlying hardware system (computer)
  • VM manager (VMM) or hypervisor - creates and runs virtual machines
  • Guest - process provided with virtual copy by the host
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3
Q

What is a Type 0 hypervisor?

A

Hardware based solutions that provide support for virtual machine creation and management via firmware

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4
Q

What is the difference between Type 1 and Type 2 hypervisors?

A
  • Type 1 - operating system like software built to provide virtualization
  • Type 2 - applications that run on standard operating systems but provide VMM features
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5
Q

What is paravirtualization?

A

Technique in which the guest operating system is modified to work in cooperation with the VMM to optimize performance

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6
Q

What is an emulator in the context of virtualization?

A

Allows applications written for one hardware environment to run on a very different hardware environment

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7
Q

When did virtualization first appear?

A

In IBM mainframes in 1972

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8
Q

What are the three formal definitions of virtualization?

A
  • A VMM provides an environment for programs that is essentially identical to the original machine
  • Programs running within that environment show only minor performance decreases
  • The VMM is in complete control of system resources
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9
Q

What are the benefits of virtualization?

A
  • Host system protected from VMs
  • VMs protected from each other
  • Snapshot and restore capabilities
  • Clone VMs for research or development
  • Run multiple OSes on a single machine
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10
Q

What is the purpose of nested page tables (NPTs)?

A

To maintain page-table state for both guests and the VMM

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11
Q

What is trap-and-emulate in virtualization?

A

When a guest attempts a privileged instruction, it causes a trap, allowing the VMM to gain control and handle the instruction

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12
Q

What is binary translation in virtualization?

A

A technique that translates special instructions into a new set of instructions that perform equivalent tasks

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13
Q

What is the role of hardware assistance in virtualization?

A

Provides additional support for virtualization features, improving performance and stability

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14
Q

What is the lifecycle of a virtual machine?

A

Created by VMM, resources assigned, can be deleted when no longer needed

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15
Q

What are the characteristics of Type 1 hypervisors?

A
  • Common in datacenters
  • Control and manage guest OSes
  • Provide snapshots and cloning
  • Run natively on hardware
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16
Q

What is paravirtualization’s impact on guest operating systems?

A

Guests must be modified to use VMM services, leading to increased performance

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17
Q

What is the difference between virtualization and emulation?

A

Virtualization requires the underlying CPU to be the same as the guest, while emulation allows a guest to run on a different CPU architecture

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18
Q

What is application containment?

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A

Provides virtualization-like features by segregating applications without full virtualization

19
Q

How does CPU scheduling work in a virtualized environment?

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A

VMM manages CPU allocation among guests, which may involve oversubscription and scheduling algorithms

20
Q

What methods does VMware ESX use for memory management?

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A
  • Double-paging
  • Pseudo-device driver installation
  • Balloon memory manager
21
Q

Fill in the blank: A _______ provides an environment for programs that is essentially identical to the original machine.

22
Q

True or False: Type 2 hypervisors offer better performance than Type 1 hypervisors.

23
Q

What are the challenges of memory management in virtualization?

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A

Oversubscription requiring extra management efficiency from VMM

24
Q

What are the three methods of memory management used by ESX?

Study These Flashcards
A
  • Double-paging
  • Pseudo-device driver installation
  • Deduplication
25
Define double-paging in the context of ESX memory management.
Guest page table indicates a page is in a physical frame, but the VMM moves some of those pages to backing store.
26
What is the role of the balloon memory manager in ESX?
Communicates with VMM to allocate or deallocate memory, affecting physical memory use of the guest.
27
How does deduplication work in ESX memory management?
VMM determines if the same page is loaded more than once and memory maps the same page into multiple guests.
28
Why is I/O integration easier for VMMs?
I/O has lots of variation and is somewhat segregated/flexible via device drivers.
29
What are the implications of I/O complexity for VMMs?
The more efficient the hypervisor is for I/O, the better the performance for guests.
30
List some possibilities for improved I/O performance in VMMs.
* Direct device access * DMA pass-through * Direct interrupt delivery
31
What does NAT stand for in the context of networking with VMMs?
Network Address Translation
32
What are the two types of storage management provided by VMM?
* Type 1: Storage guest root disks and config information as a disk image * Type 2: Store as files in the host OS file system
33
What does physical-to-virtual (P-to-V) conversion do?
Converts native disk blocks into VMM format.
34
What is the purpose of live migration?
To move a running guest between systems without interrupting user access.
35
List the steps involved in live migration.
* Establish connection between source and target VMM * Create new guest on target * Send read-only memory pages to target * Send read-write pages to target, marking them as clean * Repeat sending dirty pages * Freeze guest, send final state, and terminate guest on source
36
What is VMware Workstation and what does it provide?
A Type 2 VMM that runs on x86, providing virtualization for multiple guests.
37
What is the architecture-neutral bytecode output in Java?
.class files compiled from Java objects
38
What is the purpose of the Java Virtual Machine (JVM)?
To read bytecode and execute it, compiled per architecture.
39
What is the standard exit code for a successful program execution?
0
40
What does exit code 1 indicate?
A general error code when a specific error code isn't available.
41
Fill in the blank: Exit code 126 indicates that the command was found but could not be _______.
executed
42
What does exit code 255 signify?
An exit status outside the valid range (0-255).
43
What does exit code 130 indicate?
The script was terminated by the user pressing Ctrl+C.

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