请教:DB_WRITER_PROCESSES .vs. DBWR_IO_SLAVES ?

userjj

最近公司装了一台数据库, 在运行的时候压力一直都很大, 具体环境为:

solaris 8 / oracle 8.1.7.4.0 , 机器上4G内存,
当在库里执行状态查询时:

SQL>; select * from v$waitstat;

CLASS                   COUNT       TIME
------------------ ---------- ----------
data block             164294          0
system undo block           0          0
undo header                 3          0
undo block                 15          0

请问是不是数据的DBWR不够用了? 那DB_WRITER_PROCESSES 和DBWR_IO_SLAVES 我应该用哪个呢? 怎么设置呢?
多谢啦

txfy

这两个不能同时应用，主要看你的cpu颗数了！
-- If the buffer cache is very large (100,000 buffers and up) and the   application is write intensive, then db_writer_processes may be beneficial.   Note, the number of writer processes should not exceed the number of CPUs.  
-- If the application is not very write intensive (or even a DSS system) and   async I/O is available, then consider a single DBWR writer process;    If async I/O is not available then use dbwr_io_slaves.  
-- If the system is a uniprocessor(1 CPU) then implement may want to use   dbwr_io_slaves.