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Since omitting crucial details can be dangerous, the
authors believe that the accuracy and
confidence in results gained by building
scaffolding and constructing a detailed model is well
worth the extra time required. [TWL94]
- degree of detail desired Determines how
much uncertainty is minimized. It would be best to
measure and test the real system; however one approach
toward uncertainty minimization is the following.
- Use real file system code as file system simulator.
- Use real traces rather than synthetic ones.
- Calibrate disk system against real disks.
- degree of detail required Very important
for getting useful results. For example, ignoring
caching effects, which depend on rotation position in
the disk, can result in mean simulated times as much as
a factor of two larger. [TWL94]
- cost of detailed models As processors
speed up relative to I/O, a disparity in performance
increases. It becomes possible for the elapsed time
for executing the simulations to be much less than the
time required to execute the real system executing the
traced workload. [TWL94]