Intel 7xx Servers, 170 Servers manual System Level Considerations, Typical Storage Costs

Where a and b are constants. “a” is determined by adding up things like the static storage taken up by the application program. “b” is the size of the data base record plus the size of anything else, such as a Java object, that is created one entity per data base record. In some applications, “N” will refer to some freestanding fact, like the maximum number of concurrent web serving operations or the number of outstanding new orders being processed.

However, the number of data base records will very often be the source of “N.” Of course, with multiple data base files, there may be more than one actual “N”. Still, it is usually true that the record count of one file compared to another will often be available as a ratio. For instance, one could have an “Order” record and average of three and a half “Order Detail” records. As long as the ratio is reasonably stable or can be planned at a stable value, it is a matter of convention which is picked to be “N” in that case; one merely adjusts “b” in the above equation to account for what is picked for “N”.

System Level Considerations

In terms of the computer science textbooks, we are largely done. But, for someone in charge of commercial application deployment, there is one more practical thing to consider: Jobs and those newer items that now often come with them, threads.

Formally, if there is only one job or thread, then these are part of the Order(1) storage. If there are many, they end up proportional to N (e.g. One job for every 100,000 active records) and so are part of the Order(N) storage cost.

However, it is frequently possible to adjust these based on observed performance effects; the ratio to N is not entirely fixed. So, it is remains of interest to segregate these when planning storage. So, while they will not appear on the formal computer science literature, this paper will talk about Order(j) and Order(t) storage.

Typical Storage Costs

Here are typical things in modern systems and where they ordinarily sit in terms of their “entity” relationships.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
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