Simulator

This exercise uses disk.py to familiarize you with how a modern hard drive works. It has a lot of different options, and unlike most of the other simulations, it has a graphical animator to show you exactly what happens when the disk is in action.

NOTE

There is also an experimental program, disk-precise.py along with the disk.py. This version of the simulator uses the python Decimal package for precise floating-point computation, thus giving slightly better answers in some corner cases than disk.py. However, it has not been very carefully tested, so use at your own caution.

Let’s do a simple example first. To run the simulator and compute some basic seek, rotation, and transfer times, you first have to give a list of requests to the simulator. This can either be done by specifying the exact requests, or by having the simulator generate some randomly.

We’ll start by specifying a list of requests ourselves. Let’s do a single request first:

prompt> ./disk.py -a 10

At this point you’ll see:

...
REQUESTS [br '10']

For the requests above, compute the seek, rotate, and transfer times. Use -c or the graphical mode with -G ...