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