oracle服务硬件升级 调整参数

author：skate
time：2010-05-13
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.
      
    *&nb