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by Craig Shallahamer Get the book here |
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Craig Shallahamer's Blog
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. To order the book in either print or PDF form, click here. ©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. ------------------------------- SunOS, Solaris, and HP-UX have a process that is continually looking for free memory. The more memory being requested, the more aggressive this process becomes. The operating system keeps track of how many pages are scanned each second. When memory requests are light, the scan rate will be near zero. When memory is aggressively being requested, the scan rate will be greater than zero. On Solaris, administrators like to see the scan rate near zero. On SunOS and HP-UX, the key number is 200. For example, on HP-UX, if the scan rate is frequently exceeding 200, this means there is truly a lot of memory pressure. Said another way, Oracle memory requirements have exceeded the operating system's memory capacity. When available, the scan rate can be seen in vmstat reports, in the sr column. When running sar, the command-line option is -g. 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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