understanding_images.dita

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<concept outputclass="docs one-sidebar sidebar-first" id="understanding_images">
 <title>Image Overview</title>
 <shortdesc></shortdesc>
 <conbody>
 	<p>An image defines what will run on a guest instance with your Eucalyptus cloud. Typically, an
 	image contains one of the Linux distributions like CentOS, Fedora, Ubuntu, Debian or others. It could also contain one of the supported Windows server versions. The format for these is identical.</p>
 	
 	<p>Normally when we use the term "image" we mean the root file system. Once bundled, uploaded, and
 	registered with Eucalyptus, such an image is known as a Eucalyptus machine image (EMI).</p>
 	
 	<p>There are, however, other types of images that support the EMI. They are the kernel (EKI) and
 		ramdisk (ERI). They contain kernel modules necessary for
 		proper functioning of the image. Often, one set of these ERIs and EKIs are used by multiple
 		EMIs. Once loaded into the Eucalyptus cloud, the EKI and ERI are referred to by the image
 		and you don't have much interaction with them directly. </p>
 	<note type="tip">When you run an image, you can override the image's associated kernel and ramdisk
 		if necessary (for example, if you want to try out another kernel. For more information, see <xref
 	href="associating_ekieri.dita"/>.</note>
 	
 	
 	<p>To help get you started, Eucalyptus provides pre-packaged virtual machines that are ready to
 		run in your cloud. You can get them at the <xref href="http://emis.eucalyptus.com/"
 			format="html" scope="external">Eucalyptus Machine Images</xref> page. Each Eucalyptus image from
 		this site comes bundled with a correspoding EKI and ERI. You can manually download these images
 		from the web page, or you can use the Eualyptus Image Store commands to list and describe these
 		images, as well as to install an image in your cloud. For more information see the Eucalyptus
 		Image Store section in the <xref
 			href="http://www.eucalyptus.com/sites/all/modules/pubdlcnt/pubdlcnt.php?file=/sites/all/files/docs/latest/cli.pdf"
 			scope="external" format="pdf">Command
 			Line Reference Guide</xref>.</p>
 	
 	<!--<note type="note">If you are running the Ubuntu Enterprise Cloud (UEC), the images provided above will not work on the UEC when running in System or Static networking modes.</note>-->
 	

 	<p>If you find that the pre-packaged images don't meet your needs, you can add an image from an
 	existing, non-registered image, or create your own image.</p>
 	
 	<p>Once you've selected and downloaded the image(s) you plan to use, read the details in the
 	following section for directions about how to bundle, upload and register the images with your Eucalyptus cloud.</p>
 	<p>To view the status of your newly created and registered EKI, ERI, and EMI images, use the
 		<cmdname>euca-describe-images</cmdname> command. You can also view image status using the
 		Dashboard's <uicontrol>Images</uicontrol> page.</p>
 	
 	<p>Once you have added your image to Eucalyptus, see the <xref
 		href="http://www.eucalyptus.com/sites/all/modules/pubdlcnt/pubdlcnt.php?file=/sites/all/files/docs/latest/ug.pdf">User
 	Guide</xref> for information about launching and using instances based on the image. </p>
 	
 </conbody>
</concept>