9.3 Estimating Server Units

9.3 Estimating Server Units

ISD organizations support many physical servers. As mentioned, the servers can be all from one vendor or a combination of several different vendors . They are not all equal. For example, a SUN E10K server requires a great deal more time to set up as compared to a SUN Ultra 1 server. A Compaq file server will probably be installed with a different operating system than a Sequent server. The time allocation for setup and installation of the servers will be different. It would not be correct to allocate the same amount of time for each physical server. The goal is to determine a base unit of one that can be used in the resource model to estimate total time allocated to a work package. In the end, there might be 70 physical servers being supported, but only 53 units used in the calculation of time resource.

Units of one can be accomplished by a rating system. All servers independent of the vendor can be rated together. The rating system for servers is a judgmental decision based on experience, vendor estimates, and benchmarking data. Start by determining a server type/ size that will be the foundation server that is equal to a unit of one. Then, judge each other's different type server against this foundation server.

For example, if we determine a SUN E5000/E6000 server is equal to one unit, each other SUN server type is compared to the SUN E5000/E6000. What is being compared is the amount of time that it takes to complete tasks such as server setup/installation, software loading, system monitoring, and problem resolution. A SUN Ultra 1, Ultra 5, and Ultra 10, is judged to be ¼ of a unit, a SUN SPARC 1000/2000 is ¾ of a unit, and an E10K is 4 units of the E5000/E6000. A chart of the SUN server types would be as follows :

Sun Server type/size

Units Compared to Foundation server

E10K

4 units

E5000/E6000

1 unit

Sparc 1000/2000

¾ unit

E250/E450

½ unit

Ultra series

¼ unit

Sparc 5 and 10

¼ unit

To determine the number of units of one to be used in the resource model, just multiply the number of servers in each type/size to the unit rating. In the example below there are 34 physical servers, but only 24 units.

Sun Server type/size

Units Compared to Foundation server

Number of Servers

Total Units

E10K

4 units

2

8

E5000/E6000

1 unit

7

7

Sparc 1000/2000

¾ unit

9

7 rounded

E250/E450

½ unit

Ultra series

¼ unit

14

4 rounded

Sparc 5 and 10

¼ unit

12

3

-----------

Total Units

29



IT Services Costs, Metrics, Benchmarking and Marketing
IT Services: Costs, Metrics, Benchmarking and Marketing (paperback) (Enterprise Computing Series)
ISBN: 0132621959
EAN: 2147483647
Year: 2000
Pages: 93

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