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log_archive_dest_state_n=reset的含义

Oracle 作者:season0891 时间:2016-01-17 18:29:52 0 删除 编辑
今天论坛中的一个朋友问及log_archive_dest_state_n=reset的含义

LOG_ARCHIVE_DEST_STATE_n 用于指定对应的归档目录的可用状态。
RESET状态和DEFER状态功能相同。
解释:
日志传送服务将不传送redo 数据到LOG_ARCHIVE_DEST_n指定的位置,指示这个位置是有效的,但不使用它。RESET同时清除此位置有关的任何先前传输过程的error message。

[@more@]

http://download-east.oracle.com/docs/cd/B14117_01/server.101/b10823/log_transport.htm#1230951

Configuring Destinations with the LOG_ARCHIVE_DEST_n Parameter

The LOG_ARCHIVE_DEST_n initialization parameter defines up to ten (where n = 1, 2, 3, ... 10) destinations, each of which must specify either the LOCATION or the SERVICE attribute to specify where to archive the redo data. (Also, see Chapter 12 for complete information about all LOG_ARCHIVE_DEST_n attributes.)

The LOCATION and SERVICE attributes describe either a local disk location or an Oracle Net service name that represents a standby destination to which log transport services will transmit redo data. Specifying remote destinations with the SERVICE attribute ensures Data Guard can maintain a transactionally consistent remote copy of the primary database for disaster recovery.

For every LOG_ARCHIVE_DEST_n initialization parameter that you define, you can specify a corresponding LOG_ARCHIVE_DEST_STATE_n parameter. The LOG_ARCHIVE_DEST_STATE_n (where n is an integer from 1 to 10) initialization parameter specifies whether the corresponding destination is currently on (enabled) or off (disabled). Table 5-1 describes the LOG_ARCHIVE_DEST_STATE_n parameter attributes.

Table 5-1 LOG_ARCHIVE_DEST_STATE_n Initialization Parameter Attributes

AttributeDescription

ENABLE

Log transport services can transmit redo data to this destination. ENABLE is the default.

DEFER

Log transport services will not transmit redo data to this destination. This is a valid but unused destination.

ALTERNATE

This destination is not enabled, but it will become enabled if communication to its associated destination fails.

RESET

Functions the same as DEFER, but clears any error messages for the destination if it had previously failed.

Example 5-1 provides an example of one destination with the LOCATION attribute.

Example 5-1 Specifying a Local Archiving Destination

LOG_ARCHIVE_DEST_1='LOCATION=/arch1/chicago/'
LOG_ARCHIVE_DEST_STATE_1=ENABLE

Figure 5-2 shows what this simple configuration, consisting of a single local destination, would look like. The log writer process writes redo data to the online redo log file. As each online redo log file is filled, a log switch occurs and an ARCn process archives the filled online redo log file to an archived redo log file. The filled online redo log file is now available for reuse.

Figure 5-2 Primary Database Archiving When There Is No Standby Database

Text description of basicarch.gif follows.

Text description of the illustration basicarch.gif

It is important to note that the configuration shown in Figure 5-2 does not include a standby database and thus does not provide disaster-recovery protection. To make this simple configuration into a basic Data Guard configuration that provides disaster recovery, you need to add a standby database at a remote destination by specifying the SERVICE attribute.

Example 5-2 shows the initialization parameters that enable log transport services to archive the online redo log on the local destination chicago and transmit redo data to a remote standby database with the Oracle Net service name boston. The example takes the default values for all of the other LOG_ARCHIVE_DEST_n attributes:

Example 5-2 Specifying a Remote Archiving Destination

LOG_ARCHIVE_DEST_1='LOCATION=/arch1/chicago/'
LOG_ARCHIVE_DEST_STATE_1=ENABLE
LOG_ARCHIVE_DEST_2='SERVICE=boston'
LOG_ARCHIVE_DEST_STATE_2=ENABLE

These initialization parameters set up a basic Data Guard configuration that is based on the premises that log transport services will use archiver (ARCn) processes to archive to both the local and remote destinations, and the configuration provides the maximum performance level of data protection.

Although you can create a basic Data Guard configuration by specifying only the LOCATION or the SERVICE attributes on the LOG_ARCHIVE_DEST_n parameter, you can optionally specify more attributes to further define each destination's behavior. The following sections describe several of the LOG_ARCHIVE_DEST_n parameter attributes.

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