images_xen_lin.dita

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<task outputclass="docs one-sidebar sidebar-first" id="images_xen_lin">
	<title>Create Linux Image (Xen)</title>
	<shortdesc/>
	<taskbody>
		<context>
			<note type="important">Before you begin, make sure that Xen installed and properly functioning for the account you are going to use.</note>
			<p>To create a root filesystem to be used with Eucalyptus using Xen and an ISO image of the guest
				OS you want to install:</p>
			
		</context>
		<steps>
			<step>
				<cmd>Download the ISO image of the distro (guest OS) you want to install.</cmd>
			</step>
			<step>
				<cmd>Create a virtual disk with the desired size. For example, to create a 4 GiB disk:</cmd>
				<info>
					<codeblock>dd if=/dev/zero of=&lt;image_name> bs=1M count=4096</codeblock>
				</info>
			</step>
			<step>
				<cmd>Create a Xen configuration file (for example, <filepath>xen.cfg</filepath>) to boot off the
					ISO image. The file should look like the following:</cmd>
				<info>
					<codeblock>name = "bootFromISO"
kernel = "/usr/lib/xen/boot/hvmloader"
memory = 1024
builder = "hvm"
device_model = "/usr/lib64/xen/bin/qemu-dm"
boot = "d"
disk = ['file:PATH_TO_ISO,hdc:cdrom,r',
'file:PATH_TO/&lt;image_name>,sda,w']
vif = ['mac=00:01:01:00:00:03, bridge=xenbr0']
dhcp="on"
vnc = 1
vncdisplay = 7
pae = 1</codeblock>
					<note type="important">You must modify <codeph>device_model</codeph> and <codeph>kernel</codeph> since they depend on where the
						distribution puts such files. Look into the Xen package file list. Also be sure that all the options are correct for your needs.</note>
				</info>
			</step>
			<step>
				<cmd>Start the domU.</cmd>
				<info>
					<codeblock>xen create xen.cfg</codeblock>
				</info>
			</step>
			<step>
				<cmd>Connect with a VNC viewer. For example:</cmd>
				<info>
					<codeblock>xvncviewer localhost:7</codeblock>
				</info>
			</step>
			<step>
				<cmd>Install the distro as you would normally would. Do not use <codeph>lvm</codeph> or <codeph>md</codeph> and install everything in one partition. Remember the partition in which the distro is installed.</cmd>
				<info><note type="important">Most distributions will remember the network interfaces by the MAC
					address, so interfaces will always be the same (that is, <codeph>eth0</codeph> and
					<codeph>eth1</codeph> will not be inverted accidentally). In Eucalyptus you have to get the
					distribution to forget the NIC, so that every instance will see the interface as the first
					interface. To do so you may want to refer to the specific distribution. For example Debian and
					Ubuntu use <codeph>udev</codeph> so check <filepath>/etc/udev/rules.d/*net*</filepath>. CentOS
					might have something in <filepath>/etc/network-scripts/ifcfg-eth0</filepath>. Failure to do so
					may leave your instance without network.</note></info>
			</step>
			<step>
				<cmd>Stop the domU.</cmd>
			</step>
			<step>
				<cmd>Find out the starting block and the block size of the root file system.</cmd>
				<info>
					<codeblock>parted &lt;image_name></codeblock>
				</info>
			</step>
			<step>
				<cmd>Change the units to blocks.</cmd>
				<info>
					<codeblock>(parted) u
Unit? [compact]? b</codeblock>
				</info>
			</step>
			<step>
				<cmd>Print the current partition table using <codeph>p</codeph>.</cmd>
				<stepresult>Note the start for the partition you are interested in and the size. For this
					example we'll say that the start is <codeph>32256</codeph> and the size is <codeph>1024000</codeph>.</stepresult>
			</step>
			<step>
				<cmd>Extract the file system.</cmd>
				<info>
					<codeblock>dd if=&lt;image_name> of=rootfs.img bs=1 skip=32256 count=1024000</codeblock>
					
				</info>
			</step>
		</steps>
		<result>You now have a root filesystem. Make sure that it is compatible with the kernel/initrd you are using in your
			cloud environment. In particular you may want to be sure you have the
			modules of the kernel you are going to use. Then you are ready to <xref
				href="add_existing.dita">add the image</xref> to
			Eucalyptus.</result>
	</taskbody>
	
</task>