Virtualization is not expensive
Yesterday evening I received an e-mail from a colleague containing a link to an article posted on infoworld.com. This article is a summary of an speech held by Thomas Bittmann, Gartner analyst, on Tuesday at the Gartner's infrastructure, operations, and data center summit in Sydney.
I do not agree with all statements made by Thomas Bittmann. If you see virtualization in a very big scope it may be true what he says, but if you narrow the meaning of virtualization down to OS virtualization available through Xen shipped by SUSE or Red Hat, you get a slightly different view of the topic. The intension of this blog is not to criticize Mr Bittmann. Its intension is more like that you should consider reading articles about virtualization very carefully and reflect the given statements with the facts and especially with your own needs.
The first statement already says, that it will be an expensive exercise "until the problems with virtualization, such as licensing, support, and emerging technologies are ironed out". I think, when you reduce your mix of operating systems you want to virtualize to only one, you get rid of two of three mentioned problems. Using RHEL5 (Red Hat Enterprise Linux 5) as hypervisor and RHEL5 as guest operating system only you don't have licensing problems, as a RHEL5 does already contain up to four licenses for virtual machines running the same OS. Also the operating system support ain't be a problem as you already have the licenses and thus the support should be included. The same should apply to SLES10 (SUSE Linux Enterprise Server 10) as hypervisor running several SLES10 guest operating system. You may have to ask Red Hat or SUSE directly how licensing and support will be handled in the case of using homogeneous systems only. And, as Xen is already a part of RHEL5 and SLES10, I don't think that you have to spend huge amounts of money to get support for this particular technology.
A statement, which we should look very close to is "There are still [problems] with virtualization in support and software licensing and not everything can be virtualized; ...". I don't agree with the first part (support and licensing) as already described in the last paragraph. Nevertheless, I fully agree to the second part of the statement, that not everything can be virtualized. Before starting to implement some kind of virtualization I strongly encourage you to review your current data center infrastructure and your software system landscape. For SAP this could mean that you only want to virtualize Demo, Test, Development and QA systems, but not your production systems. The possibility to provide demo, test, dev and qa systems in a matter of seconds, because you already have images is a very nice feature. This feature normally does not apply for production systems. What I want to say is, review the life cycle and the usage types of your SAP systems and then think about virtualization itself.
Several other statements simply do not apply to the kind of OS virtualization I'm talking about. I don't look at thin clients when using Xen on the server side. If you narrow down your expectations about virtualization to two or three main topics, Xen already delivers them to you. For my daily work I checked which topics must be met by a technology to satisfy my needs. These are as follows. The possibility to:
* provide systems in a matter of minutes using remote tools (which means no more walk to the data center)
* change system resources like CPU/memory/disks on the fly during runtime
* stable, secure and insular environments to work with
Xen from Red Hat and SUSE gives me all three of them. All three do also apply when using SAP software. If you need more application server for your system, just add a new machine or change the system resources on the fly. Also the insular principle between the virtual machines provides a simple but powerful encapsulation between systems.
As you can see, virtualization is not expensive in may case, because the needs I defined are met by a technology which is already available, and furthermore stable, fast and secure. Maybe you give it a try with some of your test systems and see for yourself if it mets your needs as well.
