What Constitutes High Availability?
In my book High Availability: Design, Techniques and Processes (Prentice Hall PTR, 2001, ISBN 0-13-096288-0), we emphasize the fact that a system is perceived as always available to the end user if the following statements are true:
The system is accessible when the user needs it.
The system always provides timely, accurate results.
The system is easy enough for the user to actually use it.
The critical element here is that high availability is measured from the user's point of view. For example, it doesn't really matter if the IT guys just installed a gigabit LAN for the office, if the users still can't access the server because it rebooted by itself and the administrator isn't around to input the power-on password. (It should have been disabled.) Nor do users care if the latest version of the mail server was just purchased, if they still don't get all their email because the mailbox is always full. (The user should have been given more mail storage space.) And will they really jump for joy at the next version of an application that now requires them to remember to convert some of their files when used on older systems? (Should have migrated all users.) Experience tells us they certainly won't.
When your IT organization makes a decision to outsource a service that was traditionally provided by them directly, it's creating an intermediary layer of service delivery between IT and the end users. This intermediary layer should only be visible to the IT organization, and should be transparent to the end user. This is the simplest measure of a successful outsourcing: that the end users continue to think that the service is provided by their internal IT organization, and the quality of service provided is the same, if not better.
The following sections provide some "golden rules" to follow in outsourcing.