ITPub博客

首页 > Linux操作系统 > Linux操作系统 > HA parameters

HA parameters

原创 Linux操作系统 作者:mambo_shen 时间:2009-10-13 21:22:52 0 删除 编辑

DB_BLOCK_CHECKING

 

Oracle checks a block by going through the data in the block, making sure it is logically self-consistent. Block checking can often prevent memory and data corruption. Block checking typically causes 1% to 10% overhead, depending on workload and the parameter value. The more updates or inserts in a workload, the more expensive it is to turn on block checking. You should set DB_BLOCK_CHECKING to FULL if the performance overhead is acceptable. For backward compatibility the use of FALSE (implying OFF) and TRUE (implying FULL) is preserved.

 

DB_BLOCK_CHECKSUM

 

Checksums allow Oracle to detect corruption caused by underlying disks, storage systems, or I/O systems. If set to FULL, DB_BLOCK_CHECKSUM also catches in-memory corruptions and stops them from making it to the disk. Turning on this feature in TYPICAL mode causes only an additional 1% to 2% overhead. In the FULL mode it causes 4% to 5% overhead. Oracle recommends that you set DB_BLOCK_CHECKSUM to TYPICAL. For backward compatibility we preserve use of TRUE (implying TYPICAL) and FALSE (implying OFF) values.

 

FAST_START_MTTR_TARGET

 

When fast-start checkpointing is enabled, Oracle automatically maintains the speed of checkpointing so that the requested MTTR is achieved. Setting the value to 0 will disable this functionality.

 

LOG_BUFFER

 

In general, larger values for LOG_BUFFER reduce redo log file I/O, particularly if transactions are long or numerous. In a busy system, a value 65536 or higher is reasonable.

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/16348200/viewspace-616469/,如需转载,请注明出处,否则将追究法律责任。

请登录后发表评论 登录
全部评论

注册时间:2008-10-09

  • 博文量
    86
  • 访问量
    74071