Images
A disk image is a file containing the complete contents and structure of an operating system; it is launched on a physical server to create your instance. Xandr provides base CentOS and Windows disk images available in the images
directory on the public network attached storage share. See Available Operating Systems. You can also create and launch any Linux-based distribution such as domUs, Ubuntu, Debian, etc. See How to Create Custom Images for more information. Please contact support at https://help.xandr.com if you wish to run a non-Linux-based OS.
The format of an Xandr image is a gzipped tar archive (also known as a tarball) with the extension .tgz
or .tar.gz
. Here is an example on Linux of how to convert an .iso
file to a valid Xandr format.
mkdir /mnt/debian mount -o loop debian_64.iso /mnt/debian cd /mnt/debian tar cvzf /tmp/debian.fs.tgz .
You can reach base CentOS and Windows images from the public share folder, which has been mounted on your management instance by Xandr Support. Here is a truncated manage-instance launch command example:
manage-instance launch --share-name=public --path=images/centos5-base/centos-current.fs.tgz . . .
Your own images can be stored in and reached from your private share folder.
Further Reading
- Information on the CentOS Yum Repository
- To launch an instance, use the manage-instance command
- To create an image from an offline Xndr instance, use the manage-instance bundle command
- To learn more about your private share, see Network Attached Storage
- Available Operating Systems
Kernels
XNDR uses a Linux-based kernel that is Xen-aware, which means it knows it is running as a virtual machine and will reduce any performance-degrading effects of virtualization. For this reason a kernel inherent in your Linux-based disk image will be replaced with the Xandr-compiled kernel. Once your instance is running, you can make modifications to the kernel by installing your own custom kernel modules.
Please also note that there are a number of Xen-specific kernel modules that allow you to run applications like Samba client, IPFilter/IPTables, etc. in a virtualized environment. These modules can be found as an RPM package at the location below. We strongly recommend you install this RPM on your custom images so that you will be able to use all the features of your instances:
http://yum.local.appnexus.net/amd64/centos5/appnexus/RPMS/kernel-xen-2.6.18-128.7.1.el5.x86_64.rpm
If you wish to use a kernel other than the default kernel in your instance, please see Available and Custom Kernels.
As always, please create a ticket at https://help.xandr.com if you have any questions or concerns.