Page 131 - How Cloud Computing Is Transforming Business and Why You Cant Afford to Be Left Behind

O VERCOMING RESISTANCE T O THE CL OUD

the Amazon Machine Image, that was unique to EC2. The file
format of a virtual machine allows it to be saved as a single file,
combining the application, the operating system, and all its
parts. That file, or virtual appliance, can then be stored, re-
trieved, and moved around like an iTune or any other digital
file. Amazon has published no details on what constitutes an

AMI file or how it’s different from other Xen hypervisor files.
But it’s different enough to prevent the standard, generally
available Xen hypervisor from being able to run it.
If you like sending workloads to EC2, you accept the re-
quirement that you use AMIs and find a way to build workloads
in them. But if you decide that EC2 is no longer for you, those
workloads are not easily extracted and moved someplace else,

unless you are able to convert them on your own into some
other format, such as VMware’s Virtual Machine Disk format
(VMDK), Microsoft’s Virtual Hard Disk (VHD), or the neutral
import/export Open Virtualization Format (OVF).
In addition, Amazon’s AMI format is meant for use in the
EC2 cloud only. It’s not available for its customers to use in
their internal data centers. In the long run, Amazon will surely
provide tools that will make it easy to operate a hybrid cloud
between EC2 and customer data centers and migrate work-

loads back and forth. But as of today, that’s a stumbling block.
As lock-ins go, this is a modest one and, in various multi-
step ways, reversible. But nevertheless, it exists as a barrier for
the ill-prepared end user. To get workloads into EC2, Amazon
supplies free tools to create AMIs. Tools to build AMIs are also
available from independent suppliers, such as rPath. There are
even vendors who will help you convert your existing virtual

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