In 《DSI401_dump_crashes_corrupt.pdf》,you can find how to use the parameter of “lock_sga” and “_use_ism” and what is the definition of these two parameters.

The initialization parameter lock_sga allows a DBA to instruct the system to call a portspecific routine to lock physical memory for the SGA. An undocumented initialization parameter _use_ism allow ports to specify an SGA that shares some virtual memory constructs across processes and on versions of Solaris with no dynamic ISM ( DISM) support.

It seems to you that the lock_sga must be set ture.bucause it can lock the physical memory for SGA and do not page in & out(i.e. do not use swap memory).but,is it so good?

Also in 《DSI401_dump_crashes_corrupt.pdf》, you can find these words:

whnever the SGA is locked in the physical memory, Oracle9i will lock the amount of memory equal to the SGA_MAX_SIZE specification. In other words, an attempt lock the SGA in the physical memory will result in the locking of memory equal to the maximum SGA size. While this guarantees the ability to grow the SGA dynamically, it can result in some aste of system memory especially if the current SGA size is significantly smaller than the GA_MAX_SIZE specification. Therefore, in order to truly take advantage of the dynamic GA, the use of the LOCK_SGA parameter (if available) should be discouraged. On Solaris, the USE_ISM parameter is set to TRUE by default for performance reasons.

The associate knowledge of LOCK_SGA and _USE_ISM is that:

 http://tolywang.itpub.net/post/48/385042

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