Brother-Eagle® DB2 Performance
Advice: BP Hit%

At the database level, across all bufferpools defined in the database, this metric represents the percentage of occurrences that a required page (data or index) is already present in the bufferpool and need not be loaded from disk. The higher the percentage, the better - generally.

Brother-Eagle will indicate a warning if the Database Bufferpool Hit Percentage is less than, or equal to, 95%. Brother-Eagle will indicate an alert status if the Database Bufferpool Hit Percentage is less than, or equal to, 80%.

If the Bufferpool Hit Percentage is lower than 80%, performance improvements may possibly be obtained by increasing the size of bufferpools in the database. However, you are more likely to improve bufferpool hit ratios by reducing scans (asynchronous prefetch I/O reads).

DO NOT BE FOOLED by a high bufferpool hit percentage. It is very easy to obtain a 99% or higher bufferpool hit ratio and still have ENORMOUS performance problems present within the database.

• For example, you might have a 1GB bufferpool, a 100MB table, and an SQL statement that scans all 100MB of table data every time it executes! This happens often! BEWARE.

Before packing up your tuning hat and going home satisfied that your database is well tuned, be certain to consider the values of these health metrics:

• Sync Read%
• IX Read Efficiency

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