oracle服务硬件升级---调整参数

布满荆棘的人生 2022-07-12 09:15 223阅读 0赞

author：skate

time：2010-05-13

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1)If memory increases and you're 64-bit,  e.g  8G to 16G,  Oracle SGA and related parameters need adjust; So are some the Unix kernel parameters.  
  
2)As for CPU related configuration,  some  parameters, based on CPU\_count,  need to adjust,  
    \* cpu\_count  
    \* fast\_start\_parallel\_rollback  
    \* parallel\_max\_servers  
    \* log\_buffer  
    \* db\_block\_lru\_latches  
  
Please read below:  
"Why is cpu\_count important?  
  
The Oracle cpu\_count is determined when you start Oracle.  The cpu\_count affects the Oracle cost-based optimizer through many calculated parameters that use cpu\_count as their basis and are considered every time that Oracle creates an execution plan for a SQL statement.  A doubled setting for cpu\_count can result in changes to your explain plans when moving from a single to multiple CPUs or when you increase the number of CPUs in your system.  
  
The cpu\_count is used to determine the settings for several important init.ora parameters:  
  
·         fast\_start\_parallel\_rollback - The default value is 2 times the number of CPU of your system, but some DBAs recommend setting this value to 4 times the cpu\_count.  
  
    \*   db\_block\_lru\_latches – This defaults to the following formula : (CPU\_COUNT x 6) or (DB\_BLOCK\_BUFFERS/50), whichever is less. In earlier releases it defaulted to CPU\_COUNT/2.  If you set DB\_BLOCK\_LRU\_LATCHES higher than this max value on systems where it is available (<9i) or set the undocumented parameter \_DB\_BLOCK\_LRU\_LATCHES higher, then Oracle just ignores this and sets it internally to the above calculated value. However it will be set to Num\_pools x (CPU\_COUNT/2) if multiple buffer pools (default, recycle, keep and any of the multi-block size pools) are setup.  
        
    \*     parallel\_max\_servers - This parameter controls the maximum number of OPQ factotum processes (p000, p001) that are spawned during a parallel query when parallel\_automatic\_tuning is enabled. The DEFAULT degree of parallelism is calculated as:  
  
                   CPU\_COUNT \* PARALLEL\_THREADS\_PER\_CPU  
  
·         log\_buffer and redo copy patches - The number of CPUs is used to determine the value of log\_buffer if the log\_buffer parameter is not set in the initialization parameters. For details on LGWR, click here.  There is still argument about whether the cpu\_count influences the behavior of actions against the log\_buffer. Of course other important internalized parameters that deal with the log buffer are redo copy latches (2 times the number of CPUs when cpu\_count>1) and redo allocation latches."  
  
[http://www.dba-oracle.com/oracle\_tips\_cpu\_count\_wrong.htm][http_www.dba-oracle.com_oracle_tips_cpu_count_wrong.htm]  
  
3)If CPU number increases,  your oracle licensing need to update if your license is based on CPU numbers.  
  
Please refer  
[http://www.oracle.com/corporate/pricing/multicore\_faq.pdf][http_www.oracle.com_corporate_pricing_multicore_faq.pdf]

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[http_www.dba-oracle.com_oracle_tips_cpu_count_wrong.htm]: http://www.dba-oracle.com/oracle_tips_cpu_count_wrong.htm
[http_www.oracle.com_corporate_pricing_multicore_faq.pdf]: http://www.oracle.com/corporate/pricing/multicore_faq.pdf