OCP-1Z0-053-V12.02-511题

511.You have configured flash recovery area in your database and you set the following Initialization

parameters for your database instance:

LOG_ARCHIVE_DEST 1 = ,,LOCATION=/disk1/arch MANDATORY'

LOG _ARCHIEVE_DEST 2 = ,,LOCATION=/disk2/arch'

LOG_ARCHIVK_DEST_3 = ,,LOCATION=/diSk3/arch

LOG_ARCH1VK_DEST_4 = ' LOCATION=/disk4/arch'

LOG_ARCHIVE_MIN-SUCCEED_DEST = 2

While the database instance is functional, you realized that the destination set by the

LOG_ARCHIVE_DEST_I parameter Is not available for the archived redo log file to be created in. All redo

log groups have been used. What happens in an event of log switch?

A. The online redo log file Is not allowed to be overwritten.

B. The archived redo log files are written to the flash recovery area until the MANDATORY destination is

made available.

C. The database instance will crash because the archived redo log file cannot be created in a destination

set as MANDATORY.

D. The destination set by the LOG_ARCHIVE_DEST_1 parameter is ignored and the archived redo log

files are created in the next two available locations to guarantee archive log success.

Answer: D

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e25494/archredo.htm#ADMIN11346

The optional initialization parameter LOG_ARCHIVE_MIN_SUCCEED_DEST=n determines the minimum number of destinations to which the database must successfully archive a redo log group before it can reuse online log files. The default value is 1. Valid values for n are 1 to 2 if you are using duplexing, or 1 to 31 if you are multiplexing.

 The LOG_ARCHIVE_DEST_n parameter lets you specify whether a destination is OPTIONAL (the default) or MANDATORY. The LOG_ARCHIVE_MIN_SUCCEED_DEST=n parameter uses all MANDATORY destinations plus some number of non-standby OPTIONAL destinations to determine whether LGWR can overwrite the online log. 

When you specify a value for LOG_ARCHIVE_MIN_SUCCEED_DEST=n, Oracle Database will treat at least one local destination as MANDATORY, because the minimum value for LOG_ARCHIVE_MIN_SUCCEED_DEST is 1.

题中共有4个LOG _ARCHIEVE_DEST，而LOG_ARCHIVE_MIN-SUCCEED_DEST = 2，即意味着必须有两个能归档成功，而LOG_ARCHIVE_DEST 1 是指定MANDATORY，即要求它必须归档成功，但此时LOG_ARCHIVE_DEST 1不可用，根据LOG_ARCHIVE_MIN-SUCCEED_DEST = 2，保证接下来的两个归档地址必须归档成功。