10/26/2006

Dear Team ___:

Our infrastructure for medical records is shown in Figure 6.5 (page 313).

I am informed by my hospital administrators that 99.9% availability is needed for this infrastructure.

1. What is our current level of availability? (I suspect that it is not very high.)

2. If that current level is less than 99.9%, what is the least investment that we would have to make in order to attain this 99.9% availability?

Attached are the availability specifications and costs for the components of the infrastructure and for alternative components. Note that we can enhance our infrastructure by purchasing more of the existing components or some of the alternative components. I need to know the price and configuration of the least cost solution. All of the functionally equivalent components may be configured in parallel. (For example, an S8-application server may be configured in parallel with another S8-application server or with an S8X-application server, and an X7-switch may be configured in parallel with an X7X-switch or with an X3X-switch or with another X7-switch, but not with an F7-firewall. And an application server may not be configured in parallel with a router, and a web server may not be configured in parallel with an application server. And so forth.)

It may be that this problem requires the development of an algorithm or the purchase of a specialized software product to find the least cost solution. If that is the case, please try to come up with some configuration which meets the 99.9% availability requirement and its cost, though not necessarily the least cost configuration, and, if you can, outline the algorithm that we would need to have implemented to find the least cost configuration or identify the specialized software product.

Thank you,

Jacqueline Smith

Chief Information Officer

Very Big Hospital Corporation

p.s. Please include an influence diagram influence of my personal decision as to whether I should back this investment or not; also sketch out decision trees for my personal decision and for the decision from the point of view of the corporation as a whole.

-----Attachment A -- Components in existing infrastructure

component            availability        cost (in thousands)

X3-router                          99%              10

F7-firewall                        96%                6

S7-policy server                98%                7

S8-application server          98%              25

S9-web server                    95%              20

S3-database server            96%               27

X7-switch                            99.5%              40

-----Attachment B -- Functionally equivalent components that we might combine with existing components in our infrastructure

component            availability        cost (in thousands)

X3X-router                              99.5%                      15

X1X-router                              98%                         3

F7X-firewall                            99.56%                  12

S7X-policy server                    99.7%                    17

S8X-application server              98.9%                   29

S9X-web server                        99.5%                    25

S3X-database server                99.99%                   37

X7X-switch                                99.99%                  60

X3X-switch                                99.0%                  20