There is also an assumption that the annual run rate for hardware stays the same year over year. This is false. Maintenance and support costs frequently rise as equipment ages, especially after three years. Performance or capacity requirements can drive the need for constant upgrades or system expansion. Other costs can creep up over time as well. In fact, it is possible for the TCO to be so bad that there never is a positive return on investment (ROI).
It is also true that many hidden costs exists that are not evident during the decision time. For example, a mainframe comes with multiple assist processors that handle the I/O whereas each x86 server must handle its own I/O. This results in the mainframe having greater throughput, running at a much higher utilization rate and growing total capacity at a slower rate.
Additionally, many features included in the mainframe software must be separately purchased on other system types. This hidden cost usually does not become evident until time of purchase.
Lastly, mainframe storage is shared while all non-mainframe servers use shared-nothing storage, which means many more multiple copies of data exist in the x86 environment. In some cases the storage costs for the x86 systems can be two to six times those on the mainframe.
You are not buying a mainframe so why care? Vendors are experts at setting up scenarios and providing the stories on how their solutions are best for solving the problem. But the vendor solution may not tell the full story or map well to your business needs. Thus, business and IT executives have to determine their current and future (three to five years) business requirements and understand all of the acquisition and operational cost parameters before meeting with vendors so that their needs do not become vendor-biased. A little technical knowledge is needed too so that executives can separate the hype from reality and extract missing pieces of the pie.
Finally, if the skills to do all this do not exist within the company, executives should seek outside assistance. The expense will pay for itself and prevent you from picking the wrong solution, overspending for unneeded components, or overpaying.
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