Re: calculate hit ratio using v$buffer_pool_statistics

> Thanks for the advice. Previously, I failed to see how increasing the
> db writer can increase db performance.

The DBWR can become a bottleneck. Before one accesses the data in a block, that block must be read into the Buffer Cache. If your instance has been running any length of time, then it is likely that the Buffer Cache is full and no more free slots exist. So the least recently used blocks are "aged out" of the cache. If those blocks are dirty (i.e. have changed), then those blocks must be written out to disk *before* that buffer becomes free and is available for use. In a highly active system with lots of changes to the buffer cache, the DBWR can become a bottleneck in freeing up buffers. So increasing the performance of DBWR can be important.

HTH,
Brian

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