Customers on distributed platforms have had forms of virtualization for a while now. Storage virtualization has been the main tool through the use of SANs. While this form of virtualization clearly offers cost savings, it's limited in terms of its impact. Machine virtualization has the potential to offer dramatically increased savings over whats possible through just storage. Products like IBMs LPAR technology, VMware and other competitors can potentially offer significant operations costs saving to customers employing them. Obviously, this is a technology that can be misused but thats for the next post. I wanted to go over the main reasons for the much larger potential cost savings through machine virtualization in this post. These will all be well known to Z/OS, 390 or iSeries customers as they have had them for some time now. We're seeing this technology become available on commodity boxes now for the first time.
One of the promises of virtualization is lower costs. Heres where I think the main cost savings lie.
Less physical boxes in the data center
Obviously, there are fewer physical boxes required. You may be able to get 5 to 10 x reduction depending on how much risk you take. The more virtual machines on a physical box, the more risk you can that you'll overload it. But, less physical boxes means less data center cost. Data centers cost a lot of money in terms of power, physical space, construction costs etc.
Administration savings
A virtual machine is as expensive as a physical one from a continous administration point of view. It's still an operating system image which requires the same administration as a physical one. The main saving is that the virtual machine is fixed, the hardware is always the same regardless of the physical platform. Virtualized devices like network cards, displays, storage controllers are constant. When a new type of physical box arrives, you just deploy the virtual image on to it, you don't need to make a new image or install new device drivers etc. You just need to make sure your virtualization software can run on the new physical server. This is the main administrative benefit. You only really have one hardware platform to worry about, the virtual one and it doesn't change. Obviously, it's also cheaper to migrate an application from one box to another and creating a virtual image is a lot cheaper than creating a real one because the OS install is identical. You just copy the image and update host names. Storage virtualization would allow you to easily copy existing drives but if the new box has different hardware specs then the copied image won't run. This is a thing of the past with machine virtualization, the hardware is always the same.
Hardware standardization in a market where new hardware is released almost constantly.
Standardization of 'hardware platform' is the main benefit and most of the cost benefits come from this capability.
Vendors pushing a virtualization marketing story frequently use over provisioning as the main evil to eliminate with this technology. However, overvirtualization (I think this is my own term, I haven't seen it used before) is a potential evil of this technology. I'll discuss this in the next post.
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