Step 4: Setting the initial buffer pool sizes and characteristics
About this task
- The value in the Planned field, shown at the top of the page, is the sum of the Total virtual pool size and the Total hiper pool size. These are the pool sizes (in MB) that you have specified in Step 1: Selecting a pattern file.
- The object placement and sizing algorithm has used
this total storage to calculate the initial virtual sizes for the
individual buffer pools, based on the object placements specified
User-definedcolumn on the previous page.
- The sum of all buffer pool sizes (the recommended number of pages for a buffer pool, multiplied by the page size of the buffer pool in MB) yields the planned size in MB.
- By default, the sizing algorithm allocates a minimum buffer pool size of 20% of the average buffer pool size for buffer pools to which objects are assigned.
- If you change the virtual buffer pool size of one of the listed
buffer pools, the
Newsize, at the top of the page, reflects the new sum (in MB). Initially, Planned and New show the same value. (Small differences are possible because only integer pages are calculated, not fractions.)
- To change a value, double-click the value and edit it. Then, press Enter or select a different field.
Note that the size of buffer pools that no longer have objects assigned to them is set to zero. When you apply the recommendations from the object placement and buffer pool sizing, access to objects assigned to these buffer pools is disabled.
- Shows the name of the buffer pool.
- VP Size [pages]
- Shows the recommended virtual buffer pool size, in number of pages, for the affected buffer pool.
- VP Seq [%]
- Shows the recommended virtual pool sequential steal threshold (VPSEQT) for the affected buffer pool. This is the portion of the buffer pool that can be occupied by sequentially accessed pages. For more details, see Thresholds — Virtual sequential in The Buffer Pool Characteristics section.
- DefWrite [%]
- Shows the recommended deferred write threshold (DWQT) for the affected buffer pool. This is the percentage of the buffer pool that can be occupied by unavailable pages. For more details, see Thresholds — Deferred write in The Buffer Pool Characteristics section.
- VertDefWrite [%]
- Shows the recommended vertical deferred write threshold (VDWQT) for the affected buffer pool. This is the percentage of the buffer pool that can be occupied by updated pages of a single page set. For more details, see Thresholds — Vert deferred write in The Buffer Pool Characteristics section.
- Review the recommended initial buffer pool sizes and thresholds. Adjust them, if required.
- Click Finish, or Back to
return to the previous page.
When the object placement wizard finishes, the result is immediately shown in a new browser window. In addition, the result is saved in the Results subfolder of the Object Placement folder for later viewing.
- Continue with Viewing the result of an optimization cycle, or close the browser window and return to the Buffer Pool Analyzer main window.