Re: Oracle question from a Sys. admin, re: Solaris performance

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Fri, 04 Mar 2005 19:57:59 +0100
Message-ID: <bpbh211ab0e7fcc15rgedo8avgoi4kbv8j@4ax.com>

On 4 Mar 2005 08:09:15 -0800, tonij67_at_hotmail.com wrote:

>I don't understand this statement; I can see not enough memory causing
>increased reads, but how could too much memory cause paging? Inst
>paging caused by *lack* of memory?
>
>Unless Oracle is doing something different with real memory and swap
>that I am not aware of...

The SGA is located in *virtual* memory. *Virtual* memory can be bigger than physical memory. As soon as virtual memory exceeds physical memory you have a problem. The O/S will address this by writing the Least Recently Used page to disk in a page file. If paging is excessive and a process is doing nothing, many O/Ses will swap the complete process to disk.

Hope the issue is now clear.

--
Sybrand Bakker, Senior Oracle DBA

Received on Fri Mar 04 2005 - 12:57:59 CST