[working/Evergreen.git] / 1.6 / admin / ServersideInstallationVirtual.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <chapter xmlns="http://docbook.org/ns/docbook" xmlns:xi="http://www.w3.org/2001/XInclude" xmlns:xl="http://www.w3.org/1999/xlink">
3         <title>Installing In Virtualized <systemitem class="osname">Linux</systemitem> Environments</title>
4         <section xml:id="serversideinstallation-virtual">
5                 <title>Overview</title>
6                 <para>This section describes the installation of Evergreen software in so-called "virtualized" software environments. Evergreen software runs as a native application on any of several well-known x86 (32-bit) and x86-64 (64-bit) <systemitem class="osname">Linux</systemitem> distributions including <systemitem class="osname">Ubuntu</systemitem> and <systemitem class="osname">Debian</systemitem> but it does not run as a native application on the <systemitem class="osname">Microsoft Windows</systemitem> operating system. However, it is possible to execute Evergreen on a <systemitem class="osname">Windows</systemitem> host system by running it within a virtual Linux-guest installation, which itself executes on the <systemitem class="osname">Windows</systemitem> system. The <systemitem class="osname">Linux</systemitem> environment is fully emulated and acts (within limits) just as if it were executing on a real standalone system.</para>
7                 <para>This technique of emulating a <systemitem class="osname">Linux</systemitem> environment on a <systemitem class="osname">Windows</systemitem> host is a practical way to install and run an Evergreen system if it is not possible to dedicate a physical machine solely as a <systemitem class="osname">Linux</systemitem> host for Evergreen. This architecture is not recommended for large scale systems since there are performance limitations to running Evergreen in a virtualized environment. However, it is a reasonable architecture for smaller experimental systems, as a proof of concept, or as a conference-room pilot.</para>
8                 <section>
9                         <title>Installing Virtualization Software</title>
10                         <para>As described above, Evergreen can be installed on top of an emulated <systemitem class="osname">Linux</systemitem> environment. The <systemitem class="osname">Linux</systemitem> environment, in turn, is installed on top of a software application such as <application>"VirtualBox"</application>, <application>"VMware"</application> or <application>"VirtualPC"</application> which must first be installed on the <systemitem class="osname">Windows</systemitem> system. This section contains step-by-step examples that show installing popular virtualization applications on a <systemitem class="osname">Windows</systemitem> host system. Following this section are further descriptions of installing <systemitem class="osname">Linux</systemitem> and Evergreen systems using that virtualization software.</para>
11                         <section xml:id="serversideinstallation-virtual-vbox-install">
12                                 <title>Installing <application>"VirtualBox"</application> Virtualization Software</title>
13                                 <para>This section reviews installation of the <application>"VirtualBox"</application> application on <systemitem class="osname">WindowsXP Professional (SP2)</systemitem>. Download <application>VirtualBox</application> from their official website: <ulink url="http://download.virtualbox.org/virtualbox/3.2.8/VirtualBox-3.2.8-64453-Win.exe">http://download.virtualbox.org/virtualbox/3.2.8/VirtualBox-3.2.8-64453-Win.exe</ulink>, then run the executable file. Continue with the steps shown in the next five figures until the software has been successfully installed:</para>
14                                 <figure>
15                                         <title>Starting the Windows installation file</title>
16                                         <mediaobject>
17                                                 <imageobject>
18                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-1.png" scalefit="1" width="70%"/>
19                                                 </imageobject>
20                                         </mediaobject>
21                                 </figure>
22                                 <figure>
23                                         <title>Welcome to <application>VirtualBox</application> setup wizard</title>
24                                         <mediaobject>
25                                                 <imageobject>
26                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-2.png" scalefit="1" width="70%"/>
27                                                 </imageobject>
28                                         </mediaobject>
29                                 </figure>
30                                 <figure>
31                                         <title>Accept the license agreement</title>
32                                         <mediaobject>
33                                                 <imageobject>
34                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-3.png" scalefit="1" width="70%"/>
35                                                 </imageobject>
36                                         </mediaobject>
37                                 </figure>
38                                 <figure>
39                                         <title>Waiting for files to be copied</title>
40                                         <mediaobject>
41                                                 <imageobject>
42                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-4.png" scalefit="1" width="70%"/>
43                                                 </imageobject>
44                                         </mediaobject>
45                                 </figure>
46                                 <figure>
47                                         <title>Installation is complete</title>
48                                         <mediaobject>
49                                                 <imageobject>
50                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-5.png" scalefit="1" width="70%"/>
51                                                 </imageobject>
52                                         </mediaobject>
53                                 </figure>
54                         </section>
55                         <section>
56                                 <title>Installing <application>"VMware"</application> Virtualization Software</title>
57                                 <para>This section reviews installation of the <application>"VMware"</application> application on <systemitem class="osname">WindowsXP Professional (SP2)</systemitem>. Download <application>VMware</application> from their official website: <ulink url="">link</ulink>, then run the executable file. Continue with the steps shown in the figures until the software has been successfully installed:</para>
58                                 <figure>
59                                         <title>Starting the Windows installation file</title>
60                                         <mediaobject>
61                                                 <imageobject>
62                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-1.png" scalefit="1" width="75%"/>
63                                                 </imageobject>
64                                         </mediaobject>
65                                 </figure>
66                                 <indexterm>
67                                         <primary>ZZZ-REVIEW</primary>
68                                         <secondary>ADD INFO ON VMWARE</secondary>
69                                 </indexterm>
70                                 <caution>ADD INFO ON VMWARE</caution>
71                                 <para>At this point, <application>VirtualBox</application> has been installed, started for the first time, and a new virtual machine (VM) has been created. This VM is the environment in which the <systemitem class="osname">Linux</systemitem> / Evergreen installation will execute. Please continue in <xref linkend="serversideinstallation-virtual-install-linux-ev"/> with the installation of the <systemitem class="osname">Linux</systemitem> / Evergreen distribution.</para>
72                         </section>
73                         <section>
74                                 <title>Installing <application>"VirtualPC"</application> Virtualization Software</title>
75                                 <para>This section reviews installation of the <application>"VirtualPC"</application> application on <systemitem class="osname">WindowsXP Professional (SP2)</systemitem>. Download <application>VMware</application> from their official website: <ulink url="">link</ulink>, then run the executable file. Continue with the steps shown in the figures until the software has been successfully installed:</para>
76                                 <figure>
77                                         <title>Starting the Windows installation file</title>
78                                         <mediaobject>
79                                                 <imageobject>
80                                                         <imagedata fileref="../media/serversideinstallation-virtual-vbox-install-1.png" scalefit="1" width="75%"/>
81                                                 </imageobject>
82                                         </mediaobject>
83                                 </figure>
84                                 <indexterm>
85                                         <primary>ZZZ-REVIEW</primary>
86                                         <secondary>ADD INFO ON VIRTUALPC</secondary>
87                                 </indexterm>
88                                 <caution>ADD INFO ON VIRTUALPC</caution>
89                                 <para>At this point, <application>VirtualBox</application> has been installed, started for the first time, and a new virtual machine (VM) has been created. This VM is the environment in which the <systemitem class="osname">Linux</systemitem> / Evergreen installation will execute. Please continue in <xref linkend="serversideinstallation-virtual-install-linux-ev"/> with the installation of the <systemitem class="osname">Linux</systemitem> / Evergreen distribution.</para>
90                         </section>
91                 </section>
92                 <section xml:id="serversideinstallation-virtual-install-linux-ev">
93                         <title>Installing <systemitem class="osname">Linux</systemitem> / Evergreen on Virtualization Software</title>
94                         <para>After the virtualization software is installed and running, there are two ways to continue with installing <systemitem class="osname">Linux</systemitem> and Evergreen software in the new virtualized environment:</para>
95                         <orderedlist>
96                                 <listitem>
97                                         <para>Download and install a prebuilt software image that contains a working <systemitem class="osname">Linux</systemitem> / Evergreen system (see <xref linkend="serversideinstall-virtual-prebuilt"/> for details)</para>
98                                 </listitem>
99                                 <listitem>
100                                         <para>Manually install a <systemitem class="osname">Linux</systemitem> guest system, then manually install Evergreen on it (see <xref linkend="serversideinstall-virtual-manual"/> for details)</para>
101                                 </listitem>
102                         </orderedlist>
103                         <para>We review each method in the following sections.</para>
104                         <section xml:id="serversideinstall-virtual-prebuilt">
105                                 <title>Download and install a prebuilt software image</title>
106                                 <para>You can download a prebuilt software image that, when installed with your virtualization software, emulates a <systemitem class="osname">Linux</systemitem> guest system containing a running Evergreen distribution. The image is essentially a snapshot of a hard disk from a fully configured, functional <systemitem class="osname">Linux</systemitem> system with Evergreen already installed.</para>
107                                 <para>We recommend this approach if you wish to get Evergreen running quickly with minimal attention to configuration. After reviewing only a few configuration details you can have a working Evergreen system that integrates smoothly with the rest of your network. See <xref linkend="serversideinstall-virtual-versions"/> for a list of prebuilt software images that are currently available to download and install</para>
108                                 <note>DISCLAIMER: The following virtual images have been contributed by members of the Evergreen community for the purposes of testing, evaluation, training, and development.</note>
109                                 <table xml:id="serversideinstall-virtual-versions">
110                                         <title>Linux / Evergreen Virtual Images</title>
111                                         <tgroup align="left" cols="4" colsep="1" rowsep="1">
112                                                 <thead>
113                                                         <row>
114                                                                 <entry>Linux Version</entry>
115                                                                 <entry>Evergreen Version</entry>
116                                                                 <entry>Image</entry>
117                                                                 <entry>Comments</entry>
118                                                         </row>
119                                                 </thead>
120                                                 <tbody>
121                                                         <row>
122                                                                 <entry>Debian lenny (5.0)</entry>
123                                                                 <entry></entry>
124                                                                 <entry>
125                                                                         <ulink url="http://www.open-ils.org/~denials/Evergreen1601_DebianLenny.zip"> download </ulink>
126                                                                 </entry>
127                                                                 <entry>VirtualBox image</entry>
128                                                         </row>
129                                                         <row>
130                                                                 <entry>Ubuntu karmic koala (9.10)</entry>
131                                                                 <entry></entry>
132                                                                 <entry>
133                                                                         <ulink url="http://www.open-ils.org/~denials/Evergreen-1600-Karmic.zip"> download </ulink>
134                                                                 </entry>
135                                                                 <entry></entry>
136                                                         </row>
137                                                         <row>
138                                                                 <entry>Ubuntu hardy heron (8.04)</entry>
139                                                                 <entry></entry>
140                                                                 <entry>
141                                                                         <ulink url="http://open-ils.org/dokuwiki/doku.php?id=server:1.2:ubuntu804:readme"> download </ulink>
142                                                                 </entry>
143                                                                 <entry>VirtualBox image; no preloaded data</entry>
144                                                         </row>
145                                                         <row>
146                                                                 <entry>Debian etch (4.0)</entry>
147                                                                 <entry></entry>
148                                                                 <entry>
149                                                                         <ulink url="http://open-ils.org/dokuwiki/doku.php?id=vmware:debian"> download </ulink>
150                                                                 </entry>
151                                                                 <entry>VMware image; preloaded with 13,000 Gutenberg records</entry>
152                                                         </row>
153                                                         <row>
154                                                                 <entry>Ubuntu gutsy gibbon (7.10)</entry>
155                                                                 <entry></entry>
156                                                                 <entry>
157                                                                         <ulink url="http://www.open-ils.org/downloads/vmware/Evergreen_1.2.1.4_on_Ubuntu_7.10.zip"> download </ulink>
158                                                                 </entry>
159                                                                 <entry>VMware image</entry>
160                                                         </row>
161                                                         <row>
162                                                                 <entry>Gentoo</entry>
163                                                                 <entry>1.1.5</entry>
164                                                                 <entry>
165                                                                         <ulink url="http://www.open-ils.org/~denials/Evergreen_1.1.5_Gentoo_x86.zip"> download </ulink>
166                                                                 </entry>
167                                                                 <entry>VMware image</entry>
168                                                         </row>
169                                                 </tbody>
170                                         </tgroup>
171                                 </table>
172                                 <indexterm>
173                                         <primary>ZZZ-REVIEW</primary>
174                                         <secondary>ADD LIST OF OTHER PREBUILT IMAGES</secondary>
175                                 </indexterm>
176                                 <caution>ADD LIST OF OTHER PREBUILT IMAGES</caution>
177                                 <para>For the following example, we have already installed the <application>VirtualBox</application> application (see <xref linkend="serversideinstallation-virtual-vbox-install"/> for details). Continue with the steps as shown; refer to the accompanying figures for further information:</para>
178                                 <procedure>
179                                         <step>Start VirtualBox for the first time and select <menuchoice><guimenu>File</guimenu><guimenuitem>VirtualBox Media Manager</guimenuitem><guimenuitem>Add</guimenuitem></menuchoice> to locate the prebuilt software image just downloaded (the example shows it was extracted from the original <literal>.ZIP</literal> file into a temporary directory <literal>C:\temp</literal>). See <xref linkend="serversideinstallation-virtual-vm-install-2"/> for details.</step>
180                                         <step>After selecting the file, click <guibutton>Open</guibutton> to import it (see <xref linkend="serversideinstallation-virtual-vm-install-3"/> for details).</step>
181                                         <step>Then click <guibutton>OK</guibutton> to save the selection and return to the VirtualBox Media Manager (see <xref linkend="serversideinstallation-virtual-vm-install-4"/> for details).</step>
182                                         <step>Click <guibutton>New</guibutton> to start the "Virtual Machine Wizard", then <guibutton>Next</guibutton> to continue and create a new virtual machine (VM) <xref linkend="serversideinstallation-virtual-vm-install-5"/>).</step>
183                                         <step>Create a new name for the VM and set the operating system type, then click <guibutton>Next</guibutton> (see <xref linkend="serversideinstallation-virtual-vm-install-6"/>).</step>
184                                         <step>Set the memory size (we chose the default value of 512Mb), then click <guibutton>Next</guibutton> (see <xref linkend="serversideinstallation-virtual-vm-install-7"/>).</step>
185                                         <step>Edit the Virtual Hard Disk configuration settings; click the radio boxes "Boot Hard Disk" and "Use existing hard disk" and ensure that the disk name "Evergreen1601_DebianLenny.vmdk" is selected. Click <guibutton>Finish</guibutton> to finish the setup (see <xref linkend="serversideinstallation-virtual-vm-install-8"/>).</step>
186                                         <step>
187                                                 <para>Install the <application>VirtualBox Guest Additions</application> (really a required upgrade to VirtualBox)</para>
188                                                 <indexterm>
189                                                         <primary>ZZZ-REVIEW</primary>
190                                                         <secondary>ADD INFO ON INSTALLING VIRTUALBOX GUEST ADDITIONS</secondary>
191                                                 </indexterm>
192                                                 <caution>ADD INFO ON INSTALLING VIRTUALBOX GUEST ADDITIONS</caution>
193                                         </step>
194                                         <step>Return to VirtualBox and see the summary of the VM just created. Click <guibutton>Start</guibutton> to boot the new VM (see <xref linkend="serversideinstallation-virtual-vm-install-9"/>).</step>
195                                         <step>See the start of the <systemitem class="osname">Linux</systemitem> boot sequence. Choose "Debian Gnu/Linux, kernel 2.6.26-2-686" from the startup menu and type <guibutton>Enter</guibutton> to start <systemitem class="osname">Linux</systemitem> and Evergreen (see <xref linkend="serversideinstallation-virtual-vm-install-11"/>). After some delay you should see the command line prompt: <literal>debian-lenny login:</literal>  .  Log in with username <literal>root</literal> and password <literal>evergreen</literal> to continue (see <xref linkend="serversideinstallation-virtual-vm-install-14"/>).</step>
196                                 </procedure>
197                                 <para>At this point you have a running <systemitem class="osname">Linux</systemitem> / Evergreen system. If you need to modify the Evergreen configuration in any way, review the sectons of the standard Evergreen installation instructions in <xref linkend="serversideinstallation-ubuntudebian"/> that deal with configuration.</para>
198                                 <figure xml:id="serversideinstallation-virtual-vm-install-2">
199                                         <title>Starting <application>VirtualBox</application> for the first time</title>
200                                         <mediaobject>
201                                                 <imageobject>
202                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-2.png" scalefit="1" width="70%"/>
203                                                 </imageobject>
204                                         </mediaobject>
205                                 </figure>
206                                 <figure xml:id="serversideinstallation-virtual-vm-install-3">
207                                         <title>Selecting the software image in Virtual Media Manager</title>
208                                         <mediaobject>
209                                                 <imageobject>
210                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-3.png" scalefit="1" width="70%"/>
211                                                 </imageobject>
212                                         </mediaobject>
213                                 </figure>
214                                 <figure xml:id="serversideinstallation-virtual-vm-install-4">
215                                         <title>New software image added to <application>VirtualBox</application></title>
216                                         <mediaobject>
217                                                 <imageobject>
218                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-4.png" scalefit="1" width="75%"/>
219                                                 </imageobject>
220                                         </mediaobject>
221                                 </figure>
222                                 <figure xml:id="serversideinstallation-virtual-vm-install-5">
223                                         <title>Creating a new VM</title>
224                                         <mediaobject><imageobject><imagedata fileref="../media/serversideinstallation-virtual-vm-install-5.png" scalefit="1" width="75%"/></imageobject>
225 gg                                      </mediaobject>
226                                 </figure>
227                                 <figure xml:id="serversideinstallation-virtual-vm-install-6">
228                                         <title>Setting the VM name and OS type</title>
229                                         <mediaobject>
230                                                 <imageobject>
231                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-6.png" scalefit="1" width="75%"/>
232                                                 </imageobject>
233                                         </mediaobject>
234                                 </figure>
235                                 <figure xml:id="serversideinstallation-virtual-vm-install-7">
236                                         <title>Setting memory size</title>
237                                         <mediaobject>
238                                                 <imageobject>
239                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-7.png" scalefit="1" width="75%"/>
240                                                 </imageobject>
241                                         </mediaobject>
242                                 </figure>
243                                 <figure xml:id="serversideinstallation-virtual-vm-install-8">
244                                         <title>Setting up the Virtual Hard Disk</title>
245                                         <mediaobject>
246                                                 <imageobject>
247                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-8.png" scalefit="1" width="75%"/>
248                                                 </imageobject>
249                                         </mediaobject>
250                                 </figure>
251                                 <figure xml:id="serversideinstallation-virtual-vm-install-9">
252                                         <title>Finishing definition of new VM</title>
253                                         <mediaobject>
254                                                 <imageobject>
255                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-9.png" scalefit="1" width="75%"/>
256                                                 </imageobject>
257                                         </mediaobject>
258                                 </figure>
259                                 <figure xml:id="serversideinstallation-virtual-vm-install-10">
260                                         <title>Summary of the new VM</title>
261                                         <mediaobject>
262                                                 <imageobject>
263                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-10.png" scalefit="1" width="75%"/>
264                                                 </imageobject>
265                                         </mediaobject>
266                                 </figure>
267                                 <figure xml:id="serversideinstallation-virtual-vm-install-11">
268                                         <title>Selecting VM from startup menu</title>
269                                         <mediaobject>
270                                                 <imageobject>
271                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-11.png" scalefit="1" width="75%"/>
272                                                 </imageobject>
273                                         </mediaobject>
274                                 </figure>
275                                 <figure xml:id="serversideinstallation-virtual-vm-install-12">
276                                         <title>Starting the new VM</title>
277                                         <mediaobject>
278                                                 <imageobject>
279                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-12.png" scalefit="1" width="75%"/>
280                                                 </imageobject>
281                                         </mediaobject>
282                                 </figure>
283                                 <figure xml:id="serversideinstallation-virtual-vm-install-13">
284                                         <title>Starting the new VM (continued)</title>
285                                         <mediaobject>
286                                                 <imageobject>
287                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-13.png" scalefit="1" width="75%"/>
288                                                 </imageobject>
289                                         </mediaobject>
290                                 </figure>
291                                 <figure xml:id="serversideinstallation-virtual-vm-install-14">
292                                         <title>Logging into the new VM</title>
293                                         <mediaobject>
294                                                 <imageobject>
295                                                         <imagedata fileref="../media/serversideinstallation-virtual-vm-install-14.png" scalefit="1" width="75%"/>
296                                                 </imageobject>
297                                         </mediaobject>
298                                 </figure>
299                         </section>
300                         <section xml:id="serversideinstall-virtual-manual">
301                                 <title>Manually install <systemitem class="osname">Linux</systemitem> and Evergreen</title>
302                                 <para>You can manually install a <systemitem class="osname">Linux</systemitem> guest system and Evergreen on your virtualization software.</para>
303                                 <para>We recommend this approach if you need to specially configure either the <systemitem class="osname">Linux</systemitem> system or Evergreen itself. This will require a detailed review of both <systemitem class="osname">Linux</systemitem> and Evergreen configuration details. You are essentially doing a normal Evergreen installation on a <systemitem class="osname">Linux</systemitem> system; it just happens that <systemitem class="osname">Linux</systemitem> is running within a virtualized environment. Refer to <xref linkend="serversideinstallation-ubuntudebian"/> for information on the normal Evergreen installation, then continue with this section.</para>
304                                 <para>For the following example, we have already installed the <application>VirtualBox</application> application (see <xref linkend="serversideinstallation-virtual-vbox-install"/> for details). Continue with the steps as shown; refer to the accompanying figures for further information:</para>
305                                 <procedure>
306                                         <step>
307                                                 <para>Download and install a standard <systemitem class="osname">Ubuntu</systemitem> distribution in <application>"VirtualBox"</application>.</para>
308                                                 <para>You can download a software image of a prebuilt <systemitem class="osname">Ubuntu</systemitem> distribution and immediately import it into <application>"VirtualBox"</application> , or you can download and install 
309 </para>
310                                                 <indexterm>
311                                                         <primary>ZZZ-REVIEW</primary>
312                                                         <secondary>ADD DETAILS ON MANUAL INSTALLATION OF LINUX</secondary>
313                                                 </indexterm>
314                                                 <caution>ADD DETAILS ON MANUAL INSTALLATION OF LINUX</caution>
315                                         </step>
316                                         <step>
317                                                 <para>Start (boot) <systemitem class="osname">Ubuntu</systemitem>.</para>
318                                                 <indexterm>
319                                                         <primary>ZZZ-REVIEW</primary>
320                                                         <secondary>ADD DETAILS ON VM LINUX BOOT SEQUENCE</secondary>
321                                                 </indexterm>
322                                                 <caution>ADD DETAILS ON VM LINUX BOOT SEQUENCE</caution>
323                                         </step>
324                                         <step>
325                                                 <para>Install Evergreen on <systemitem class="osname">Ubuntu</systemitem>.</para>
326                                                 <indexterm>
327                                                         <primary>ZZZ-REVIEW</primary>
328                                                         <secondary>ADD DETAILS ON MANUAL INSTALLATION OF EVERGREEN</secondary>
329                                                 </indexterm>
330                                                 <caution>ADD DETAILS ON MANUAL INSTALLATION OF EVERGREEN</caution>
331                                         </step>
332                                 </procedure>
333                                 <para>At this point, the <systemitem class="osname">Windows</systemitem> system is hosting an <systemitem class="osname">Ubuntu</systemitem> system, which itself is hosting the Evergreen distribution. So far as Evergreen is concerned, it is happily executing in a standard <systemitem class="osname">Ubuntu</systemitem> environment and behaves exactly as if it were executing on a standalone <systemitem class="osname">Ubuntu</systemitem> system.</para>
334                                 <para>Of course, there are limitations to how well a virtualized <systemitem class="osname">Ubuntu</systemitem> system emulates a real one. The <application>"VirtualBox"</application> application itself consumes memory, and it contributes to the CPU load on the <systemitem class="osname">Windows</systemitem> host system. The emulated <systemitem class="osname">Ubuntu</systemitem> system will have less available memory and will execute more slowly than if it were a standalone system, therefore Evergreen itself will inherit some limitations from this overall environment.</para>
335                                 <para>However, this technique of using a <systemitem class="osname">Windows</systemitem> host to emulate a <systemitem class="osname">Linux</systemitem> environment is a practical way to install and run an Evergreen system even if it isn't possible to dedicate a real machine solely as a <systemitem class="osname">Linux</systemitem> host for testing. This is a reasonable architecture for simple experiments, or as a proof of concept, or as a conference-room pilot.</para>
336                         </section>
337                 </section>
338         </section>
339         <index/>
340 </chapter>