Step 1: Setting simulation parameters

About this task

When you have opened a trace data file, as described in Selecting and opening a trace data file, and have clicked the Simulation Parameters tab, the following page is displayed:
Figure 1. Simulation – The Simulation Parameters window
This figure is a graphical representation of the Simulation Parameters window from a simulation.
This page shows a list of available buffer pools and their default parameters, and it provides controls to select buffer pools and change their parameters for the simulation.
  • The top of the page shows the full path and name of the trace data file that you just opened.
  • Each row of the list represents a single buffer pool and its simulation parameters. The list shows a set of 80 selectable buffer pools in the ranges of BP0 to BP49 (the 4 KB buffer pools), BP8K0 to BP8K9 (the 8 KB buffer pools), BP16K0 to BP16K9 (the 16 KB buffer pools), and BP32K0 to BP32K9 (the 32 KB buffer pools). Initially, active buffer pools (those for which activities were recorded during the time trace data was collected and stored in the trace data file) are preselected in the Simulate column.
  • The Virtual sequential threshold field shows the percentage of the virtual buffer pool that might be occupied by sequentially accessed pages. The default value is 80%.
  • The Minimum buffer simulation size field shows the minimum buffer pool size to be simulated. The size is shown in number of buffer pool pages (whereby a single page has a size of 4 KB, 8 KB, 16 KB, or 32 KB, depending on the buffer pool).
  • The Maximum buffer simulation size field shows the maximum buffer pool size to be simulated. The size is shown in number of buffer pool pages.
  • The Interval field shows the increment by which a buffer pool size is changed (between the minimum and maximum size) during the simulation. The increment is shown in number of buffer pool pages.
You use this page to determine which buffer pools you want to include in the simulation and to specify individual simulation parameters for each selected buffer pool.
  • Select one or more buffer pools by selecting or clearing the respective check boxes. You can also use the Select all or Deselect all button to act on active buffer pools. Select the Show only active buffer pools check box to show only objects with buffer pool activity.
  • You can adjust the initial simulation parameters as required. Note that the time to perform a simulation increases with the number of buffer pools and the different buffer pool sizes to be simulated. Select the Simulate single combined buffer pool check box to run the simulation for the preselected buffer pools as a single combined buffer pool.

    Example: With the initial values shown on this page, Buffer Pool Analyzer will simulate buffer pool sizes of 1 000, 2 000, 3 000 pages, and so on, up to 20 000 pages, for a selected buffer pool.

    For practical reasons, choose a minimum and maximum buffer pool size and an interval that does not result in more than 40 buffer pool sizes per selected buffer pool. Otherwise, the time to generate the simulation result increases excessively. In addition, the simulation result becomes complex and difficult to interpret.

  • Note that you can sort the list by clicking a column header of choice one or more times. Small arrows indicate the sort order.

  1. Review your selections and the simulation parameters for each selected buffer pool. To modify a parameter, ensure that the buffer pool is selected. Then click the respective field and edit the shown value. (Internally, the minimum, maximum, and interval values are slightly rounded to avoid odd-numbered simulation cycles.)
  2. If you have already performed Step 2: Assigning objects to buffer pools, click OK to start the simulation, otherwise continue with Step 2: Assigning objects to buffer pools.