[单选]

You have the following requirements in relation to the detection of block corruption for your database instance:
1. Check for logical self-consistency of data blocks when modified in memory.
2. Checksums are calculated before and after the block change.
3. Checks are performed for the lost writes to the physical standby database.
Which method would help you perform the above checks automatically? （）

The root id is set so that direct login is disabled.  Information must be reviewed relating to when root access was obtained.  In which of the following files is this information located?（）  /var/adm/sulog 。  /var/adm/wtmp 。  /etc/security/user 。  /etc/security/failedlogi。 流动人口对城市经济、社会的影响。 A system administrator is monitoring a system that has recently shown a decrease in performance.The administrator suspects that the system may be low on memory and may be paging excessively.Which of the following commands is best to identify a possible paging problem？（） iostat。 netstat。 ps。 vmstat。 光滑极限量规用来检验螺纹的什么尺寸？ 用于企业价值评估的收益额，通常不包括（）。 利润总额。 净利润。 净现金流量。 无负债净利润。

You have the following requirements in relation to the detection of block corruption for your database instance:
1. Check for logical self-consistency of data blocks when modified in memory.
2. Checksums are calculated before and after the block change.
3. Checks are performed for the lost writes to the physical standby database.
Which method would help you perform the above checks automatically? （）