| 1 | <?xml version="1.0" encoding="UTF-8"?>
|
|---|
| 2 | <!DOCTYPE topic
|
|---|
| 3 | PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
|
|---|
| 4 | <topic xml:lang="en-us" id="virt-why-useful">
|
|---|
| 5 | <title>Why is Virtualization Useful?</title>
|
|---|
| 6 |
|
|---|
| 7 | <body>
|
|---|
| 8 | <p>
|
|---|
| 9 | The techniques and features that <ph conkeyref="vbox-conkeyref-phrases/product-name"/> provides are
|
|---|
| 10 | useful in the following scenarios:
|
|---|
| 11 | </p>
|
|---|
| 12 | <ul>
|
|---|
| 13 | <li>
|
|---|
| 14 | <p>
|
|---|
| 15 | <b outputclass="bold">Running multiple operating systems
|
|---|
| 16 | simultaneously.</b> <ph conkeyref="vbox-conkeyref-phrases/product-name"/> enables you to run
|
|---|
| 17 | more than one OS at a time. This way, you can run software
|
|---|
| 18 | written for one OS on another, such as Windows software on
|
|---|
| 19 | Linux or a Mac, without having to reboot to use it. Since you
|
|---|
| 20 | can configure what kinds of <i>virtual</i>
|
|---|
| 21 | hardware should be presented to each such OS, you can install
|
|---|
| 22 | an old OS such as DOS or OS/2 even if your real computer's
|
|---|
| 23 | hardware is no longer supported by that OS.
|
|---|
| 24 | </p>
|
|---|
| 25 | </li>
|
|---|
| 26 | <li>
|
|---|
| 27 | <p>
|
|---|
| 28 | <b outputclass="bold">Easier software
|
|---|
| 29 | installations.</b> Software vendors can use virtual
|
|---|
| 30 | machines to ship entire software configurations. For example,
|
|---|
| 31 | installing a complete mail server solution on a real machine
|
|---|
| 32 | can be a tedious task. With <ph conkeyref="vbox-conkeyref-phrases/product-name"/>, such a complex
|
|---|
| 33 | setup, often called an <i>appliance</i>, can be
|
|---|
| 34 | packed into a virtual machine. Installing and running a mail
|
|---|
| 35 | server becomes as easy as importing such an appliance into
|
|---|
| 36 | <ph conkeyref="vbox-conkeyref-phrases/product-name"/>.
|
|---|
| 37 | </p>
|
|---|
| 38 | </li>
|
|---|
| 39 | <li>
|
|---|
| 40 | <p>
|
|---|
| 41 | <b outputclass="bold">Testing and disaster
|
|---|
| 42 | recovery.</b> Once installed, a virtual machine and its
|
|---|
| 43 | virtual hard disks can be considered a
|
|---|
| 44 | <i>container</i> that can be arbitrarily frozen,
|
|---|
| 45 | woken up, copied, backed up, and transported between hosts.
|
|---|
| 46 | </p>
|
|---|
| 47 | <p>
|
|---|
| 48 | Using virtual machines enables you to build and test a
|
|---|
| 49 | multi-node networked service, for example. Issues with
|
|---|
| 50 | networking, operating system, and software configuration can
|
|---|
| 51 | be investigated easily.
|
|---|
| 52 | </p>
|
|---|
| 53 | <p>
|
|---|
| 54 | In addition to that, with the use of another <ph conkeyref="vbox-conkeyref-phrases/product-name"/>
|
|---|
| 55 | feature called <i>snapshots</i>, one can save a
|
|---|
| 56 | particular state of a virtual machine and revert back to that
|
|---|
| 57 | state, if necessary. This way, one can freely experiment with
|
|---|
| 58 | a computing environment. If something goes wrong, such as
|
|---|
| 59 | problems after installing software or infecting the guest with
|
|---|
| 60 | a virus, you can easily switch back to a previous snapshot and
|
|---|
| 61 | avoid the need of frequent backups and restores.
|
|---|
| 62 | </p>
|
|---|
| 63 | <p>
|
|---|
| 64 | Any number of snapshots can be created, allowing you to travel
|
|---|
| 65 | back and forward in virtual machine time. You can delete
|
|---|
| 66 | snapshots while a VM is running to reclaim disk space.
|
|---|
| 67 | </p>
|
|---|
| 68 | </li>
|
|---|
| 69 | <li>
|
|---|
| 70 | <p>
|
|---|
| 71 | <b outputclass="bold">Infrastructure consolidation.</b>
|
|---|
| 72 | Virtualization can significantly reduce hardware and
|
|---|
| 73 | electricity costs. Most of the time, computers today only use
|
|---|
| 74 | a fraction of their potential power and run with low average
|
|---|
| 75 | system loads. A lot of hardware resources as well as
|
|---|
| 76 | electricity is thereby wasted. So, instead of running many
|
|---|
| 77 | such physical computers that are only partially used, one can
|
|---|
| 78 | pack many virtual machines onto a few powerful hosts and
|
|---|
| 79 | balance the loads between them.
|
|---|
| 80 | </p>
|
|---|
| 81 | </li>
|
|---|
| 82 | </ul>
|
|---|
| 83 | </body>
|
|---|
| 84 |
|
|---|
| 85 | </topic>
|
|---|
