VALID_FOR in db standby

检查DG 装填：

目标主机检查mrp是否正常：
SELECT PROCESS FROM V$MANAGED_STANDBY WHERE PROCESS LIKE 'MRP%';
--若mrp没有启动，则需要启动：
alter database recover managed standby database parallel 16 disconnect from session;

源主机：确保status状态为valid
select dest_name,status,error from v$archive_dest where destination is not null;

Table 14-2 VALID_FOR Attribute Values  这些角色和logfile 仅仅对当前数据库有效，对远端数据库无效

VALID_FOR Definition	Primary Role	Physical Standby Role	Logical Standby Role
ONLINE_LOGFILE, PRIMARY_ROLE	Active	Inactive	Invalid
ONLINE_LOGFILE, STANDBY_ROLE	Inactive	Invalid	Active
ONLINE_LOGFILE, ALL_ROLES	Active	Invalid	Active
STANDBY_LOGFILE, PRIMARY_ROLE	Error	Error	Error
STANDBY_LOGFILE, STANDBY_ROLE	Invalid	Active	Active
STANDBY_LOGFILE ALL_ROLES	Invalid	Active	Active
ALL_LOGFILES, PRIMARY_ROLE	Active	Inactive	Invalid
ALL_LOGFILES, STANDBY_ROLE	Invalid	Active	Active
ALL_LOGFILES, ALL_ROLES	Active	Active	Active

DB_UNIQUE_NAME

指定这个日志存放的数据库日志地址

Specifies a unique name for the database at this destination.

#########信息不准确

关于admin guide中v$archive_dest的status这一列有好7种值，文档说得太抽象，于是本文做了一部分实验来看看这些值到底在什么情况下会显示。

VALID -- The user has properly initialized the destination, which is available for archiving.

INACTIVE -- The user has not provided or has deleted the destination information.

ERROR -- An error occurred creating or writing to the destination file; refer to error data.

FULL -- Destination is full (no disk space).

DEFERRED -- The user manually and temporarily disabled the destination.

DISABLED -- The user manually and temporarily disabled the destination following an error; refer to error data.

BAD PARAM -- A parameter error occurred; refer to error data.

另外还有一种ALTERNATE 的status。

-------TEST begins----------