Craig Shallahamer's Blog
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You were brought to this page based on an internet search
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The text below is an except from the book,
Oracle Performance Firefighting, written by
Craig Shallahamer of
OraPub, Inc.
Figures and tables are not included on this page, only their reference.
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©2009, 2010 by Craig Shallahamer. This is copyrighted material.
Please—Out of respect for those involved in the creation of the book and also for
their familes, we ask you to respect the copyright both in intent and deed. Thank you.
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<p>The v$session_wait parameters are documented to provide the number of blocks being written, but I have personally not found this accurate. Once again, I turn to operating system tracing. Figure 6-22 shows the result of tracing an active database writer process. There are three columns: the pwrite command, the number of bytes written, and the number of 8KB Oracle blocks written. Your system will look different, but don't be surprised to see the database writer submit a write request of more than 100 Oracle 8KB blocks!
p><p>Figure 6-22. Operating system tracing is the reliable way to see how many Oracle blocks the database writer is actually submitting for each request. The far-right column is the number of 8KB Oracle blocks written. The largest multiblock database writer write shown in this figure is 36.
p><p>It's the database writer's responsibility to write the dirty buffers to disk. Run this simple query:
p>
©2009, 2010 by Craig Shallahamer. This is copyrighted material.
Please—Out of respect for those involved in the creation of the book and also for
their familes, we ask you to respect the copyright both in intent and deed. Thank you.
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