個人自行閱讀時候，翻譯的文檔暴心。因為比較渣妓盲，如果有更合理或者錯誤的地方煩勞告知，我會做修改专普。
Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data. Oracle Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruptions. Oracle Data Guard maintains these standby databases as copies of the production database. Then, if the production database becomes unavailable because of a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage. Oracle Data Guard can be used with traditional backup, restoration, and cluster techniques to provide a high level of data protection and data availability. Oracle Data Guard transport services are also used by other Oracle features such as Oracle Streams and Oracle GoldenGate for efficient and reliable transmission of redo from a source database to one or more remote destinations.
Oracle Data Guard可確保企業(yè)數(shù)據(jù)的高可用性悯衬，數(shù)據(jù)保護和災(zāi)難恢復(fù)。 Oracle Data Guard提供了一套全面的服務(wù)檀夹，可以創(chuàng)建筋粗，維護，管理和監(jiān)視一個或多個備用數(shù)據(jù)庫炸渡，從而使生產(chǎn)上的Oracle數(shù)據(jù)庫能夠在災(zāi)難和數(shù)據(jù)損壞中生存娜亿。 Oracle Data Guard將這些備用數(shù)據(jù)庫作為生產(chǎn)數(shù)據(jù)庫的副本進行維護。然后蚌堵，如果生產(chǎn)數(shù)據(jù)庫由于計劃或計劃外中斷而變得不可用买决，則Oracle Data Guard可以將任何備用數(shù)據(jù)庫切換到生產(chǎn)角色，從而最大限度地減少與中斷相關(guān)的停機時間吼畏。 Oracle Data Guard可以與傳統(tǒng)的備份督赤，恢復(fù)和集群技術(shù)結(jié)合使用，以提供的數(shù)據(jù)保護的高級別和數(shù)據(jù)可用性宫仗。 Oracle Data Guard傳輸服務(wù)也被其他Oracle功能部件（如Oracle Streams和Oracle GoldenGate）高效的用于從源數(shù)據(jù)庫到一個或多個遠程目標(biāo)進行可靠的重做傳輸够挂。
With Oracle Data Guard, administrators can optionally improve production database performance by offloading resource-intensive backup and reporting operations to standby systems.
使用Oracle Data Guard，管理員可以通過將資源密集型備份和報告分流到備用系統(tǒng)來選擇性地提高生產(chǎn)數(shù)據(jù)庫性能藕夫。
This chapter includes the following topics that describe the highlights of Oracle Data Guard:
■Oracle Data Guard Configurations
■Oracle Data Guard Services
■Oracle Data Guard Broker
■Oracle Data Guard Protection Modes
■Client Failover
■Oracle Data Guard and Complementary Technologies
■Summary of Oracle Data Guard Benefits
本章包括以下主題描述Oracle Data Guard的主要內(nèi)容：
■Oracle Data Guard 配置
■Oracle Data Guard 服務(wù)
■Oracle Data Guard 代理
■Oracle Data Guard 保護模式
■客戶端故障轉(zhuǎn)移
■Oracle Data Guard 和 互補技術(shù)
■Oracle Data Guard 優(yōu)點概述
1.1 Oracle Data Guard Configurations
An Oracle Data Guard configuration can contain one primary database and up to thirty destinations. The members of an Oracle Data Guard configuration are connected by Oracle Net and may be dispersed geographically. There are no restrictions on where the members of an Oracle Data Guard configuration are located as long as they can communicate with each other. For example, you can have a standby database in the same data center as the primary database, along with two standbys in another data center.
Oracle Data Guard配置可以包含一個主數(shù)據(jù)庫和最多三十個目標(biāo)孽糖。 Oracle Data Guard配置的成員由Oracle Net連接枯冈，可能在地理上分散。 只要Oracle Data Guard配置的成員可以彼此通信办悟，就不會對其位置進行限制尘奏。 例如，您可以在與主數(shù)據(jù)庫相同的數(shù)據(jù)中心中具有備用數(shù)據(jù)庫病蛉，在另一個數(shù)據(jù)中心中具有兩個備用數(shù)據(jù)庫炫加。
You can manage primary and standby databases using either the SQL command-line interface or the Oracle Data Guard broker interfaces. The broker provides a command-line interface (DGMGRL) and a graphical user interface that is integrated in Oracle Enterprise Manager Cloud Control.
您可以使用SQL命令行界面或Oracle Data Guard代理接口管理主數(shù)據(jù)庫和備用數(shù)據(jù)庫。 代理提供了集成在Oracle Enterprise Manager Cloud Control中的命令行界面（DGMGRL）和圖形用戶界面铺然。
1.1.1 Primary Database
An Oracle Data Guard configuration contains one production database, also referred to as the primary database, that functions in the primary role. This is the database that is accessed by most of your applications.
The primary database can be either a single-instance Oracle database or an Oracle Real Application Clusters (Oracle RAC) database.
Oracle Data Guard配置包含一個生產(chǎn)數(shù)據(jù)庫俗孝，也稱為主數(shù)據(jù)庫，在主角色中運行魄健。 這是大多數(shù)應(yīng)用程序訪問的數(shù)據(jù)庫赋铝。
主數(shù)據(jù)庫可以是單實例Oracle數(shù)據(jù)庫或Oracle Real Application Clusters（Oracle RAC）數(shù)據(jù)庫。
1.1.2 Standby Databases
A standby database is a transactionally consistent copy of the primary database. Using a backup copy of the primary database, you can create up to thirty standby databases and incorporate them into an Oracle Data Guard configuration. Once created, Oracle Data Guard automatically maintains each standby database by transmitting redo data from the primary database and then applying the redo to the standby database.
備用數(shù)據(jù)庫是主數(shù)據(jù)庫的事務(wù)一致性副本沽瘦。 使用主數(shù)據(jù)庫的備份副本革骨，您可以創(chuàng)建最多三十個備用數(shù)據(jù)庫，并將它們合并到Oracle Data Guard配置中析恋。 創(chuàng)建后良哲，Oracle Data Guard通過從主數(shù)據(jù)庫傳輸重做數(shù)據(jù)，然后將重做應(yīng)用于備用數(shù)據(jù)庫助隧，自動維護每個備用數(shù)據(jù)庫筑凫。
Similar to a primary database, a standby database can be either a single-instance Oracle database or an Oracle RAC database.
與主數(shù)據(jù)庫類似，備用數(shù)據(jù)庫可以是單實例Oracle數(shù)據(jù)庫或Oracle RAC數(shù)據(jù)庫喇颁。
The types of standby databases are as follows:
備用數(shù)據(jù)庫的類型如下
■Physical standby database
Provides a physically identical copy of the primary database, with on disk database structures that are identical to the primary database on a block-for-block basis. The database schema, including indexes, are the same. A physical standby database is kept synchronized with the primary database, through Redo Apply, which recovers the redo data received from the primary database and applies the redo to the physical standby database.
提供主數(shù)據(jù)庫的物理上相同的副本漏健，在磁盤數(shù)據(jù)庫結(jié)構(gòu)上，這些數(shù)據(jù)庫結(jié)構(gòu)與基于塊的塊的主數(shù)據(jù)庫完全相同橘霎。 數(shù)據(jù)庫模式（包括索引）是相同的蔫浆。 物理備用數(shù)據(jù)庫通過重做應(yīng)用保持與主數(shù)據(jù)庫同步，恢復(fù)從主數(shù)據(jù)庫接收的重做數(shù)據(jù)并將重做應(yīng)用于物理備用數(shù)據(jù)庫姐叁。
As of Oracle Database 11g Release 1 (11.1), a physical standby database can receive and apply redo while it is open for read-only access. A physical standby database can therefore be used concurrently for data protection and reporting.
從Oracle Database 11g第1版（11.1）開始瓦盛，物理備用數(shù)據(jù)庫可以在其處于只讀訪問狀態(tài)時打開并接收并應(yīng)用重做。 因此外潜，物理備用數(shù)據(jù)庫可以同時用于數(shù)據(jù)保護和報告原环。
Additionally, as of Oracle Database 11g Release 2 (11.2.0.1), a physical standby database can be used to install eligible one-off patches, patch set updates (PSUs), and critical patch updates (CPUs), in rolling fashion. For more information about this functionality, see the My Oracle Support note 1265700.1 at http://support.oracle.com.
此外，從Oracle Database 11g第2版（11.2.0.1）開始处窥，物理備用數(shù)據(jù)庫可用于以滾動方式安裝合格的一次性修補程序嘱吗，修補程序集更新（PSU）和關(guān)鍵修補程序更新（CPUs）。 有關(guān)此功能的詳細信息，請參閱My Oracle Support說明1265700.1谒麦，網(wǎng)址為http://support.oracle.com俄讹。
■Logical standby database
Contains the same logical information as the production database, although the physical organization and structure of the data can be different. The logical standby database is kept synchronized with the primary database through SQL Apply, which transforms the data in the redo received from the primary database into SQL statements and then executes the SQL statements on the standby database.
包含與生產(chǎn)數(shù)據(jù)庫相同的邏輯信息，雖然數(shù)據(jù)的物理組織和結(jié)構(gòu)可以不同绕德。 邏輯備用數(shù)據(jù)庫通過SQL 應(yīng)用與主數(shù)據(jù)庫保持同步患膛，SQL 應(yīng)用將從主數(shù)據(jù)庫接收的重做數(shù)據(jù)轉(zhuǎn)換為SQL語句，然后在備用數(shù)據(jù)庫上執(zhí)行SQL語句耻蛇。
The flexibility of a logical standby database lets you upgrade Oracle Database software (patch sets and new Oracle Database releases) and perform other database maintenance in rolling fashion with almost no downtime. From Oracle Database 11g onward, the transient logical database rolling upgrade process can also be used with existing physical standby databases.
邏輯備用數(shù)據(jù)庫的靈活性允許您升級Oracle數(shù)據(jù)庫軟件（修補程序集和新的Oracle數(shù)據(jù)庫版本）踪蹬，并以滾動方式執(zhí)行其他數(shù)據(jù)庫維護，幾乎沒有停機時間臣咖。 從Oracle Database 11g開始跃捣，臨時邏輯數(shù)據(jù)庫滾動升級過程也可以與現(xiàn)有的物理備用數(shù)據(jù)庫一起使用。
■Snapshot Standby Database
A snapshot standby database is a fully updatable standby database.
快照備用數(shù)據(jù)庫是完全可更新的備用數(shù)據(jù)庫夺蛇。
Like a physical or logical standby database, a snapshot standby database receives and archives redo data from a primary database. Unlike a physical or logical standby database, a snapshot standby database does not apply the redo data that it receives. The redo data received by a snapshot standby database is not applied until the snapshot standby is converted back into a physical standby database, after first discarding any local updates made to the snapshot standby database.
與物理或邏輯備用數(shù)據(jù)庫一樣枝缔，快照備用數(shù)據(jù)庫從主數(shù)據(jù)庫接收和歸檔重做數(shù)據(jù)。 與物理或邏輯備用數(shù)據(jù)庫不同蚊惯，快照備用數(shù)據(jù)庫不應(yīng)用其接收的重做數(shù)據(jù)。 在快照備用數(shù)據(jù)庫被轉(zhuǎn)換回物理備用數(shù)據(jù)庫之后灵临，在首先丟棄對快照備用數(shù)據(jù)庫進行的任何本地更新后截型，快照備用數(shù)據(jù)庫接收的重做數(shù)據(jù)才會應(yīng)用。
A snapshot standby database is best used in scenarios that require a temporary, updatable snapshot of a physical standby database. For example, you can use the Oracle Real Application Testing option to capture primary database workload and then replay it for test purposes on the snapshot standby. Note that because redo data received by a snapshot standby database is not applied until it is converted back into a physical standby, the time needed to recover from a primary database failure is directly proportional to the amount of redo data that needs to be applied.
快照備用數(shù)據(jù)庫最適用于需要物理備用數(shù)據(jù)庫的臨時可更新快照的方案儒溉。 例如宦焦，您可以使用Oracle Real Application Testing選項捕獲主數(shù)據(jù)庫工作負載，然后在快照備用數(shù)據(jù)庫上進行重放以進行測試顿涣。 請注意波闹，由于快照備用數(shù)據(jù)庫接收的重做數(shù)據(jù)在應(yīng)用程序轉(zhuǎn)換回物理備用數(shù)據(jù)庫之前不會應(yīng)用，因此從主數(shù)據(jù)庫故障恢復(fù)所需的時間與需要應(yīng)用的重做數(shù)據(jù)量成正比涛碑。
1.1.3 Far Sync Instances
An Oracle Data Guard far sync instance is a remote Oracle Data Guard destination that accepts redo from the primary database and then ships that redo to other members of the Oracle Data Guard configuration. A far sync instance manages a control file, receives redo into standby redo logs (SRLs), and archives those SRLs to local archived redo logs, but that is where the similarity with standbys ends. A far sync instance does not have user data files, cannot be opened for access, cannot run redo apply, and can never function in the primary role or be converted to any type of standby database.
Oracle Data Guard遠程同步實例是一個遠程Oracle Data Guard目標(biāo)精堕，它從主數(shù)據(jù)庫接受重做，然后將該重做發(fā)送到Oracle Data Guard配置的其他成員蒲障。 遠同步實例管理控制文件歹篓，接收重做到備用重做日志（SRLs），并將這些SRL歸檔到本地歸檔重做日志揉阎，但這是與備用數(shù)據(jù)庫的相似性結(jié)束的地方庄撮。 遠程同步實例沒有用戶數(shù)據(jù)文件，無法打開進行訪問毙籽，無法運行重做應(yīng)用程序洞斯，并且永遠不能在主角色中運行或轉(zhuǎn)換為任何類型的備用數(shù)據(jù)庫。
Far sync instances are part of the Oracle Active Data Guard Far Sync feature, which requires an Oracle Active Data Guard license.
遠程同步實例是Oracle Active Data Guard遠程同步功能的一部分坑赡，需要Oracle Active Data Guard許可證烙如。
1.1.4 Zero Data Loss Recovery Appliance
Zero Data Loss Recovery Appliance (Recovery Appliance) is an enterprise-level backup solution that provides a single repository for backups of all your Oracle databases.
零數(shù)據(jù)丟失恢復(fù)設(shè)備（恢復(fù)設(shè)備）是一種企業(yè)級備份解決方案么抗，為所有Oracle數(shù)據(jù)庫的備份提供單個存儲庫。
Recovery Appliance offloads most Oracle Database backup and restore processing to a centralized backup system. It enables you to achieve significant efficiencies in storage utilization, performance, and manageability of backups.
恢復(fù)設(shè)備將大多數(shù)Oracle數(shù)據(jù)庫備份和恢復(fù)處理卸載到集中式備份系統(tǒng)厅翔。 它使您能夠在存儲利用率乖坠，性能和備份的可管理性方面實現(xiàn)顯著的效率。
Transport of redo data to a Recovery Appliance is supported in a Data Guard configuration, as of Oracle Database 12c release 1 (12.1.0.2).
從Oracle Database 12c第1版（12.1.0.2）開始刀闷，Data Guard配置支持將恢復(fù)數(shù)據(jù)傳輸?shù)交謴?fù)應(yīng)用裝置熊泵。
1.1.5 Configuration Example
Figure 1-1 shows a typical Oracle Data Guard configuration that contains a primary database that transmits redo data to a standby database. The standby database is remotely located from the primary database for disaster recovery and backup operations. You can configure the standby database at the same location as the primary database. However, for disaster recovery purposes, Oracle recommends you configure standby databases at remote locations.
圖1-1顯示了典型的Oracle Data Guard配置，其中包含將重做數(shù)據(jù)傳輸?shù)絺溆脭?shù)據(jù)庫的主數(shù)據(jù)庫甸昏。 備用數(shù)據(jù)庫遠離主數(shù)據(jù)庫顽分，用于災(zāi)難恢復(fù)和備份操作。 您可以將備用數(shù)據(jù)庫配置在與主數(shù)據(jù)庫相同的位置施蜜。 但是卒蘸，為了災(zāi)難恢復(fù)目的，Oracle建議您在遠程位置配置備用數(shù)據(jù)庫翻默。
Figure 1-1 Typical Oracle Data Guard Configuration
(https://docs.oracle.com/database/121/SBYDB/img/sbydb042.gif)[Description of ''Figure 1-1 Typical Oracle Data Guard Configuration'']
1.2 Oracle Data Guard Services
The following sections explain how Oracle Data Guard manages the transmission of redo data, the application of redo data, and changes to the database roles:
以下部分解釋了Oracle Data Guard如何管理重做數(shù)據(jù)的傳輸缸沃，重做數(shù)據(jù)的應(yīng)用程序和數(shù)據(jù)庫角色的更改：
■Redo Transport Services
Control the automated transfer of redo data from the production database to one or more archival destinations.
控制重做數(shù)據(jù)從生產(chǎn)數(shù)據(jù)庫到一個或多個歸檔目標(biāo)的自動傳輸。
■Apply Services
Redo data is applied directly from standby redo log files as they are filled using real-time apply. If standby redo log files are not configured, then redo data must first be archived at the standby database before it is applied.
重做數(shù)據(jù)在使用實時應(yīng)用程序填充時直接從備用重做日志文件應(yīng)用修械。 如果未配置備用重做日志文件趾牧，則重做數(shù)據(jù)必須先在備用數(shù)據(jù)庫中歸檔，然后再應(yīng)用肯污。
■Role Transitions
Change the role of a database from a standby database to a primary database, or from a primary database to a standby database using either a switchover or a failover operation.
使用切換或故障轉(zhuǎn)移操作將數(shù)據(jù)庫的角色從備用數(shù)據(jù)庫更改為主數(shù)據(jù)庫翘单，或從主數(shù)據(jù)庫更改為備用數(shù)據(jù)庫。
1.2.1 Redo Transport Services
Redo transport services control the automated transfer of redo data from the production database to one or more archival destinations.
重做傳輸服務(wù)控制重做數(shù)據(jù)從生產(chǎn)數(shù)據(jù)庫到一個或多個歸檔目的地的自動傳輸蹦渣。
Redo transport services perform the following tasks:
■Transmit redo data from the primary system to the standby systems in the configuration
■Manage the process of resolving any gaps in the archived redo log files due to a network failure
■Automatically detect missing or corrupted archived redo log files on a standby system and automatically retrieve replacement archived redo log files from the primary database or another standby database
■在配置中將重做數(shù)據(jù)從主系統(tǒng)傳輸?shù)絺溆孟到y(tǒng)
■管理由于網(wǎng)絡(luò)故障而解決歸檔重做日志文件中的任何空白的過程
■在備用系統(tǒng)上自動檢測缺失或損壞的歸檔重做日志文件哄芜，并從主數(shù)據(jù)庫或其他備用數(shù)據(jù)庫自動檢索替換歸檔重做日志文件
1.2.2 Apply Services
The redo data transmitted from the primary database is written to the standby redo log on the standby database. Apply services automatically apply the redo data on the standby database to maintain consistency with the primary database. It also allows read-only access to the data.
從主數(shù)據(jù)庫傳輸?shù)闹刈鰯?shù)據(jù)將寫入備用數(shù)據(jù)庫上的備用重做日志。 應(yīng)用服務(wù)會自動在備用數(shù)據(jù)庫上應(yīng)用重做數(shù)據(jù)柬唯，以保持與主數(shù)據(jù)庫的一致性认臊。 它還允許只讀訪問數(shù)據(jù)。
The main difference between physical and logical standby databases is the manner in which apply services apply the archived redo data:
■For physical standby databases, Oracle Data Guard uses Redo Apply technology, which applies redo data on the standby database using standard recovery techniques of an Oracle database, as shown in [Figure 1-2]
Figure 1-2 Automatic Updating of a Physical Standby Database
物理和邏輯備用數(shù)據(jù)庫之間的主要區(qū)別是應(yīng)用服務(wù)應(yīng)用歸檔重做數(shù)據(jù)的方式：
對于物理備用數(shù)據(jù)庫锄奢，Oracle Data Guard使用Redo Apply技術(shù)美尸，它使用Oracle數(shù)據(jù)庫的標(biāo)準(zhǔn)恢復(fù)技術(shù)在備用數(shù)據(jù)庫上應(yīng)用重做數(shù)據(jù)，如[圖1-2]
■For logical standby databases, Oracle Data Guard uses SQL Apply technology, which first transforms the received redo data into SQL statements and then executes the generated SQL statements on the logical standby database, as shown in [Figure 1-3]
Figure 1-3 Automatic Updating of a Logical Standby Database
對于邏輯備數(shù)據(jù)庫斟薇，Oracle Data Guard使用SQL Apply技術(shù)师坎，首先將接收的重做數(shù)據(jù)轉(zhuǎn)換為SQL語句，然后在邏輯備數(shù)據(jù)庫上執(zhí)行生成的SQL語句堪滨，如圖1-3所示胯陋。
1.2.3 Role Transitions
An Oracle database operates in one of two roles: primary or standby. Using Oracle Data Guard, you can change the role of a database using either a switchover or a failover operation.
Oracle數(shù)據(jù)庫以兩種角色之一運行：主數(shù)據(jù)庫或備用數(shù)據(jù)庫。 使用Oracle Data Guard，您可以使用切換或故障轉(zhuǎn)移操作更改數(shù)據(jù)庫的角色遏乔。
A switchover is a role reversal between the primary database and one of its standby databases. A switchover ensures no data loss. This is typically done for planned maintenance of the primary system. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role.
切換是主數(shù)據(jù)庫與其一個備用數(shù)據(jù)庫之間的角色顛倒义矛。 切換確保沒有數(shù)據(jù)丟失。 這通常用于主系統(tǒng)的計劃維護盟萨。 在切換期間凉翻，主數(shù)據(jù)庫轉(zhuǎn)換為備用角色，并且備用數(shù)據(jù)庫轉(zhuǎn)換為主角色捻激。
A failover is when the primary database is unavailable. Failover is performed only in the event of a failure of the primary database, and the failover results in a transition of a standby database to the primary role. The database administrator can configure Oracle Data Guard to ensure no data loss.
故障轉(zhuǎn)移是指主數(shù)據(jù)庫不可用制轰。 僅在主數(shù)據(jù)庫發(fā)生故障的情況下執(zhí)行故障轉(zhuǎn)移，并且故障轉(zhuǎn)移會導(dǎo)致備用數(shù)據(jù)庫轉(zhuǎn)換為主要角色胞谭。 數(shù)據(jù)庫管理員可以配置Oracle Data Guard垃杖，以確保沒有數(shù)據(jù)丟失。
The role transitions described in this documentation are invoked manually using SQL statements. You can also use the Oracle Data Guard broker to simplify role transitions and automate failovers using Oracle Enterprise Manager Cloud Control or the DGMGRL command-line interface, as described in [Section 1.3]
本文檔中描述的角色轉(zhuǎn)換是使用SQL語句手動調(diào)用的丈屹。 您還可以使用Oracle Data Guard代理來簡化角色轉(zhuǎn)換调俘，并使用Oracle Enterprise Manager Cloud Control或DGMGRL命令行界面自動執(zhí)行故障切換，如[第1.3節(jié)]
1.3 Oracle Data Guard Broker
The Oracle Data Guard broker is a distributed management framework that automates the creation, maintenance, and monitoring of Oracle Data Guard configurations. You can use either the Oracle Enterprise Manager Cloud Control graphical user interface (GUI) or the Oracle Data Guard command-line interface (DGMGRL) to:
■Create and enable Oracle Data Guard configurations, including setting up redo transport services and apply services
■Manage an entire Oracle Data Guard configuration from any system in the configuration
■Manage and monitor Oracle Data Guard configurations that contain Oracle RAC primary or standby databases
■Simplify switchovers and failovers by allowing you to invoke them using either a single key click in Oracle Enterprise Manager Cloud Control or a single command in the DGMGRL command-line interface.
■Enable Oracle Data Guard fast-start failover to fail over automatically when the primary database becomes unavailable. When fast-start failover is enabled, the Oracle Data Guard broker determines if a failover is necessary and initiates the failover to the specified target standby database automatically, with no need for DBA intervention.
Oracle Data Guard代理是一種分布式管理框架旺垒，可自動創(chuàng)建彩库，維護和監(jiān)視Oracle Data Guard配置。 您可以使用Oracle Enterprise Manager Cloud Control圖形用戶界面（GUI）或Oracle Data Guard命令行界面（DGMGRL）:
■創(chuàng)建和啟用Oracle Data Guard配置先蒋，包括設(shè)置重做傳輸服務(wù)和應(yīng)用服務(wù)
■從配置中的任何系統(tǒng)管理整個Oracle Data Guard配置
■管理和監(jiān)視包含Oracle RAC主數(shù)據(jù)庫或備用數(shù)據(jù)庫的Oracle Data Guard配置
■通過允許您使用Oracle Enterprise Manager Cloud Control中的單個鍵單擊或DGMGRL命令行界面中的單個命令來調(diào)用切換和故障切換侧巨，從而簡化切換和故障切換。
■啟用Oracle Data Guard快速啟動故障切換鞭达，以在主數(shù)據(jù)庫不可用時自動故障轉(zhuǎn)移。 啟用快速啟動故障轉(zhuǎn)移后皇忿，Oracle Data Guard代理會確定是否需要故障轉(zhuǎn)移畴蹭，并自動啟動到指定目標(biāo)備用數(shù)據(jù)庫的故障轉(zhuǎn)移，而無需DBA干預(yù)鳍烁。
In addition, Oracle Enterprise Manager Cloud Control automates and simplifies:
■Creating a physical or logical standby database from a backup copy of the primary database
■Adding new or existing standby databases to an existing Oracle Data Guard configuration
■Monitoring log apply rates, capturing diagnostic information, and detecting problems quickly with centralized monitoring, testing, and performance tools
此外叨襟，Oracle企業(yè)管理器云控制可自動化和簡化：
■從主數(shù)據(jù)庫的備份副本創(chuàng)建物理或邏輯備用數(shù)據(jù)庫
■將新的或現(xiàn)有的備用數(shù)據(jù)庫添加到現(xiàn)有的Oracle Data Guard配置
■使用集中式監(jiān)控，測試和性能工具幔荒，監(jiān)控日志應(yīng)用速率糊闽，捕獲診斷信息以及快速檢測問題
1.3.1 Using Oracle Enterprise Manager Cloud Control
Oracle Enterprise Manager Cloud Control (sometimes referred to simply as Cloud Control in this book) provides a web-based interface for viewing, monitoring, and administering primary and standby databases in an Oracle Data Guard configuration. Enterprise Manager's easy-to-use interfaces, combined with the broker's centralized management and monitoring of the Oracle Data Guard configuration, enhance the Oracle Data Guard solution for high availability, site protection, and data protection of an enterprise.
Oracle企業(yè)管理器云控制（本書中有時簡稱為Cloud Control）提供了一個基于Web的界面，用于在Oracle Data Guard配置中查看爹梁，監(jiān)視和管理主數(shù)據(jù)庫和備用數(shù)據(jù)庫右犹。 企業(yè)管理器的易于使用的接口，與代理的Oracle Data Guard配置的集中管理和監(jiān)控相結(jié)合姚垃，增強了Oracle Data Guard解決方案的高可用性念链，站點保護和企業(yè)的數(shù)據(jù)保護。
Using Enterprise Manager, you can perform all management operations either locally or remotely. You can view home pages for Oracle databases, including primary and standby databases and instances, create or add existing standby databases, start and stop instances, monitor instance performance, view events, schedule jobs, and perform backup and recovery operations.
使用企業(yè)管理器，您可以在本地或遠程執(zhí)行所有管理操作掂墓。 您可以查看Oracle數(shù)據(jù)庫的主頁谦纱，包括主數(shù)據(jù)庫和備用數(shù)據(jù)庫和實例，創(chuàng)建或添加現(xiàn)有備用數(shù)據(jù)庫君编，啟動和停止實例跨嘉，監(jiān)視實例性能，查看事件吃嘿，計劃作業(yè)以及執(zhí)行備份和恢復(fù)操作祠乃。
1.3.2 Using the Oracle Data Guard Command-Line Interface
The Oracle Data Guard command-line interface (DGMGRL) enables you to control and monitor an Oracle Data Guard configuration from the DGMGRL prompt or within scripts. You can perform most of the activities required to manage and monitor the databases in the configuration using DGMGRL. See [Oracle Data Guard Broker]
Oracle Data Guard命令行界面（DGMGRL）使您能夠從DGMGRL提示符或腳本中控制和監(jiān)視Oracle Data Guard配置。 您可以使用DGMGRL執(zhí)行在配置中管理和監(jiān)視數(shù)據(jù)庫所需的大多數(shù)活動唠椭。 請參見[Oracle Data Guard Broker]
1.4 Oracle Data Guard Protection Modes
In some situations, a business cannot afford to lose data regardless of the circumstances. In other situations, the availability of the database may be more important than any potential data loss in the unlikely event of a multiple failure. Finally, some applications require maximum database performance at all times, and can therefore tolerate a small amount of data loss if any component should fail. The following descriptions summarize the three distinct modes of data protection.
在某些情況下跳纳，企業(yè)不能在任何情況下丟失數(shù)據(jù)。 在其他情況下贪嫂，數(shù)據(jù)庫的可用性可能比在多個故障的不太可能的事件中的任何潛在數(shù)據(jù)丟失更重要寺庄。 最后，一些應(yīng)用程序在任何時候都需要最大的數(shù)據(jù)庫性能力崇，因此如果任何組件出現(xiàn)故障斗塘，可以容忍少量的數(shù)據(jù)丟失。 以下描述總結(jié)了三種不同的數(shù)據(jù)保護模式亮靴。
Maximum availability This protection mode provides the highest level of data protection that is possible without compromising the availability of a primary database. With Oracle Data Guard, transactions do not commit until all redo data needed to recover those transactions has either been received in memory or written to the standby redo log (depending upon configuration) on at least one synchronized standby database. If the primary database cannot write its redo stream to at least one synchronized standby database, it operates as if it were in maximum performance mode to preserve primary database availability until it is again able to write its redo stream to a synchronized standby database.
This protection mode ensures zero data loss except in the case of certain double faults, such as failure of a primary database after failure of the standby database.
最大可用性此保護模式可提供最高級別的數(shù)據(jù)保護馍盟，而不會影響主數(shù)據(jù)庫的可用性。 使用Oracle Data Guard茧吊，事務(wù)不會提交贞岭，直到恢復(fù)這些事務(wù)所需的所有重做數(shù)據(jù)都已在內(nèi)存中接收或?qū)懭胫辽僖粋€同步備用數(shù)據(jù)庫上的備用重做日志（取決于配置）。 如果主數(shù)據(jù)庫無法將其重做流寫入至少一個同步備用數(shù)據(jù)庫搓侄，則它會像在最大性能模式下一樣操作瞄桨，以保留主數(shù)據(jù)庫可用性，直到它再次能夠?qū)⑵渲刈隽鲗懭胪絺溆脭?shù)據(jù)庫讶踪。
此保護模式確保零數(shù)據(jù)丟失芯侥，除非在某些雙重故障的情況下，例如主數(shù)據(jù)庫在備用數(shù)據(jù)庫故障后故障。
Maximum performance This is the default protection mode. It provides the highest level of data protection that is possible without affecting the performance of a primary database. This is accomplished by allowing transactions to commit as soon as all redo data generated by those transactions has been written to the online log. Redo data is also written to one or more standby databases, but this is done asynchronously with respect to transaction commitment, so primary database performance is unaffected by delays in writing redo data to the standby database(s).
This protection mode offers slightly less data protection than maximum availability mode and has minimal impact on primary database performance.
最大性能這是默認保護模式。 它提供了最高級別的數(shù)據(jù)保護辱志，而且不會影響主數(shù)據(jù)庫的性能。 這是通過允許事務(wù)在這些事務(wù)生成的所有重做數(shù)據(jù)都已寫入聯(lián)機日志后立即提交來實現(xiàn)的唉工。 重做數(shù)據(jù)也被寫入一個或多個備用數(shù)據(jù)庫，但這是相對于事務(wù)提交是異步完成的汹忠，所以主數(shù)據(jù)庫性能不受到將備用數(shù)據(jù)寫入備用數(shù)據(jù)庫的延遲的影響酵紫。
此保護模式提供比最大可用性模式少的數(shù)據(jù)保護告嘲，并且對主數(shù)據(jù)庫性能影響最小。
Maximum protection This protection mode ensures that no data loss will occur if the primary database fails. To provide this level of protection, the redo data needed to recover a transaction must be written to both the online redo log and to the standby redo log on at least one synchronized standby database before the transaction commits. To ensure that data loss cannot occur, the primary database will shut down, rather than continue processing transactions, if it cannot write its redo stream to at least one synchronized standby database.
最大保護此保護模式確保在主數(shù)據(jù)庫發(fā)生故障時不會發(fā)生數(shù)據(jù)丟失奖地。 要提供此級別的保護橄唬，在事務(wù)提交之前，恢復(fù)事務(wù)所需的重做數(shù)據(jù)必須寫入至少一個同步備用數(shù)據(jù)庫中的聯(lián)機重做日志和備用重做日志参歹。 為了確保不會發(fā)生數(shù)據(jù)丟失仰楚，如果主數(shù)據(jù)庫無法將其重做流寫入至少一個同步的備用數(shù)據(jù)庫，則主數(shù)據(jù)庫將關(guān)閉犬庇，而不是繼續(xù)處理事務(wù)僧界。
All three protection modes require that specific redo transport options be used to send redo data to at least one standby database. See Chapter 6, "Oracle Data Guard Protection Modes" for more information about setting the protection mode of a primary database.
所有三種保護模式都需要使用特定的重做傳輸選項將重做數(shù)據(jù)發(fā)送到至少一個備用數(shù)據(jù)庫。 有關(guān)設(shè)置主數(shù)據(jù)庫的保護模式的詳細信息臭挽，請參見第6章“Oracle Data Guard保護模式”捂襟。
1.5 Client Failover
A high availability architecture requires a fast failover capability for databases and database clients.
Client failover encompasses failure notification, stale connection cleanup, and transparent reconnection to the new primary database. Oracle Database provides the capability to integrate database failover with failover procedures that automatically redirect clients to a new primary database within seconds of a database failover.
高可用性架構(gòu)需要數(shù)據(jù)庫和數(shù)據(jù)庫客戶端的快速故障轉(zhuǎn)移功能。
客戶端故障轉(zhuǎn)移包括故障通知欢峰，過時的連接清除和透明重新連接到新的主數(shù)據(jù)庫葬荷。 Oracle數(shù)據(jù)庫提供了將數(shù)據(jù)庫故障轉(zhuǎn)移與故障轉(zhuǎn)移過程相集成的功能，該過程在數(shù)據(jù)庫故障轉(zhuǎn)移后的幾秒鐘內(nèi)自動將客戶端重定向到新的主數(shù)據(jù)庫纽帖。
1.5.1 Application Continuity
Application Continuity is an Oracle Database feature that enables rapid and nondisruptive replays of requests against the database after a recoverable error that made the database session unavailable.
應(yīng)用程序連續(xù)性是一種Oracle數(shù)據(jù)庫功能宠漩，可在發(fā)生使數(shù)據(jù)庫會話不可用的可恢復(fù)錯誤后，對數(shù)據(jù)庫進行快速和無中斷的請求重放懊直。
Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. Note that primary and standby databases must be licensed for Oracle RAC or Oracle Active Data Guard in order to use Application Continuity.
支持將Oracle Data Guard切換到物理備用數(shù)據(jù)庫的應(yīng)用程序連續(xù)性扒吁。 它還支持在最大可用性數(shù)據(jù)保護模式下快速啟動故障轉(zhuǎn)移到物理備用數(shù)據(jù)庫。 請注意室囊，主數(shù)據(jù)庫和備用數(shù)據(jù)庫必須獲得Oracle RAC或Oracle Active Data Guard許可才能使用應(yīng)用程序連續(xù)性雕崩。
1.6 Oracle Data Guard and Complementary Technologies
Oracle Database provides several unique technologies that complement Oracle Data Guard to help keep business critical systems running with greater levels of availability and data protection than when using any one solution by itself. The following list summarizes some Oracle high-availability technologies:
Oracle數(shù)據(jù)庫提供了幾種獨特的技術(shù)來補充Oracle Data Guard，幫助保持關(guān)鍵業(yè)務(wù)系統(tǒng)運行的可用性和數(shù)據(jù)保護級別高于單獨使用任何一個解決方案融撞。 以下列表總結(jié)了一些Oracle高可用性技術(shù)：
Oracle Real Application Clusters (Oracle RAC)
Oracle RAC enables multiple independent servers that are linked by an interconnect to share access to an Oracle database, providing high availability, scalability, and redundancy during failures. Oracle RAC and Oracle Data Guard together provide the benefits of both system-level, site-level, and data-level protection, resulting in high levels of availability and disaster recovery without loss of data:
–Oracle RAC addresses system failures by providing rapid and automatic recovery from failures, such as node failures and instance crashes. It also provides increased scalability for applications.
–Oracle Data Guard addresses site failures and data protection through transactionally consistent primary and standby databases that do not share disks, enabling recovery from site disasters and data corruption.
Oracle RAC支持由互連鏈接的多個獨立服務(wù)器盼铁，以共享對Oracle數(shù)據(jù)庫的訪問，從而在故障期間提供高可用性懦铺，可擴展性和冗余。 Oracle RAC和Oracle Data Guard一起提供系統(tǒng)級支鸡，站點級和數(shù)據(jù)級保護的優(yōu)勢冬念，從而實現(xiàn)高級別的可用性和災(zāi)難恢復(fù)，而不會丟失數(shù)據(jù)：
- Oracle RAC通過從故障（例如節(jié)點故障和實例崩潰）提供快速和自動恢復(fù)來解決系統(tǒng)故障牧挣。 它還為應(yīng)用程序提供了更高的可擴展性急前。
- Oracle Data Guard通過事務(wù)一致的主數(shù)據(jù)庫和備用數(shù)據(jù)庫解決站點故障和數(shù)據(jù)保護，這些數(shù)據(jù)庫不共享磁盤瀑构，從而實現(xiàn)從站點災(zāi)難和數(shù)據(jù)損壞進行恢復(fù)裆针。
Many different architectures using Oracle RAC and Oracle Data Guard are possible depending on the use of local and remote sites and the use of nodes and a combination of logical and physical standby databases. See [Appendix D, "Oracle Data Guard and Oracle Real Application Clusters"]
根據(jù)本地和遠程站點的使用以及節(jié)點以及邏輯和物理備用數(shù)據(jù)庫的組合刨摩，使用Oracle RAC和Oracle Data Guard的許多不同架構(gòu)都是可能的。 請參見[附錄D世吨，“Oracle Data Guard和Oracle Real應(yīng)用程序集群”
■Oracle Real Application Clusters One Node (Oracle RAC One Node)
Oracle RAC One Node provides enhanced high availability for noncluster databases, protecting them from both planned and unplanned downtime. Oracle RAC One Node provides the following:
–Always-on noncluster database services
–Better consolidation for database servers
–Enhanced server virtualization
– Lower cost development and test platform for full Oracle RAC
Oracle RAC One Node為非集群數(shù)據(jù)庫提供增強的高可用性澡刹，從而避免計劃內(nèi)和計劃外停機。 Oracle RAC One Node提供以下功能：
- 始終啟用非集群數(shù)據(jù)庫服務(wù)
- 更好合并數(shù)據(jù)庫服務(wù)
- 增強服務(wù)器虛擬化
- 降低整個Oracle RAC的成本開發(fā)和測試平臺
In addition, Oracle RAC One Node facilitates the consolidation of database storage, standardizes your database environment, and, when necessary, enables you to upgrade to a full, multinode Oracle RAC database without downtime or disruption.
As of Oracle Database 11g Release 2 (11.2.0.2), Oracle Data Guard and Oracle Data Guard broker are fully integrated with Oracle Real Application Clusters One Node (Oracle RAC One Node).
此外耘婚，Oracle RAC One Node有助于數(shù)據(jù)庫存儲的整合罢浇，標(biāo)準(zhǔn)化數(shù)據(jù)庫環(huán)境，并在必要時使您能夠升級到完整的多節(jié)點Oracle RAC數(shù)據(jù)庫沐祷，而不會停機或中斷嚷闭。
從Oracle數(shù)據(jù)庫11g第2版（11.2.0.2）開始，Oracle Data Guard和Oracle Data Guard代理與Oracle Real Application集群節(jié)點（Oracle RAC One Node）完全集成赖临。
■Flashback Database
The Flashback Database feature provides fast recovery from logical data corruption and user errors. By allowing you to flash back in time, previous versions of business information that might have been erroneously changed or deleted can be accessed once again. This feature:
–Eliminates the need to restore a backup and roll forward changes up to the time of the error or corruption. Instead, Flashback Database can roll back an Oracle database to a previous point-in-time, without restoring data files.
–Provides an alternative to delaying the application of redo to protect against user errors or logical corruptions. Therefore, standby databases can be more closely synchronized with the primary database, thus reducing failover and switchover times.
–Avoids the need to completely re-create the original primary database after a failover. The failed primary database can be flashed back to a point in time before the failover and converted to be a standby database for the new primary database.
閃回數(shù)據(jù)庫功能提供從邏輯數(shù)據(jù)損壞和用戶錯誤的快速恢復(fù)胞锰。 通過允許您及時閃回，可以再次訪問可能已錯誤更改或刪除的業(yè)務(wù)信息的先前版本兢榨。 此功能：
- 減少需要恢復(fù)備份嗅榕，并向前滾動更改到出錯或損壞的時間。 相反色乾，閃回數(shù)據(jù)庫可以將Oracle數(shù)據(jù)庫回滾到上一個時間點誊册，而不恢復(fù)數(shù)據(jù)文件。
- 提供替代方案來延遲重做的應(yīng)用程序暖璧，以防止用戶錯誤或邏輯損壞案怯。 因此，備用數(shù)據(jù)庫可以與主數(shù)據(jù)庫更緊密地同步澎办，從而減少故障轉(zhuǎn)移和切換時間嘲碱。
- 不需要在故障轉(zhuǎn)移后完全重新創(chuàng)建原始主數(shù)據(jù)庫。 故障主數(shù)據(jù)庫可以閃回到故障轉(zhuǎn)移之前的時間點局蚀，并轉(zhuǎn)換為新主數(shù)據(jù)庫的備用數(shù)據(jù)庫麦锯。
Recovery Manager (RMAN)
RMAN is an Oracle utility that simplifies backing up, restoring, and recovering database files. Like Oracle Data Guard, RMAN is a feature of the Oracle database and does not require separate installation. Oracle Data Guard is well integrated with RMAN, allowing you to:
–Use the Recovery Manager DUPLICATE command to create a standby database from backups of your primary database.
–Take backups on a physical standby database instead of the production database, relieving the load on the production database and enabling efficient use of system resources on the standby site. Moreover, backups can be taken while the physical standby database is applying redo.
–Help manage archived redo log files by automatically deleting the archived redo log files used for input after performing a backup.
RMAN是一個Oracle實用程序，可簡化數(shù)據(jù)庫文件的備份琅绅，恢復(fù)和恢復(fù)扶欣。 與Oracle Data Guard一樣，RMAN是Oracle數(shù)據(jù)庫的一項功能千扶，不需要單獨安裝料祠。 Oracle Data Guard與RMAN充分集成，允許您：
- 使用Recovery Manager DUPLICATE命令從主數(shù)據(jù)庫的備份創(chuàng)建備用數(shù)據(jù)庫澎羞。
- 在物理備用數(shù)據(jù)庫而不是生產(chǎn)數(shù)據(jù)庫上進行備份髓绽，減輕生產(chǎn)數(shù)據(jù)庫上的負載，并有效利用備用站點上的系統(tǒng)資源妆绞。 此外顺呕，可以在物理備用數(shù)據(jù)庫應(yīng)用重做時進行備份枫攀。
- 通過在執(zhí)行備份后自動刪除用于輸入的歸檔重做日志文件來管理歸檔重做日志文件。
■Global Data Services (GDS)
Global Data Services applies the Oracle RAC service model to pools of globally distributed databases, providing dynamic load balancing, failover, and centralized service management for a set of replicated databases that offer common services. The set of databases can include Oracle RAC and single-instance Oracle databases interconnected through Oracle Data Guard, Oracle GoldenGate, or any other replication technology.
GDS is integrated with Oracle Data Guard broker. This allows role-specific global services to be automatically started and stopped as appropriate when role transitions occur within an Oracle Data Guard broker configuration.
GDS allows the specification of a replication lag limit for a global service. If the lag limit is exceeded at a given replica, the global service is temporarily stopped at that replica and new client requests are routed to a replica that satisfies the lag limit. The global service is automatically restarted at the original replica when the replication lag becomes less than the lag limit.
全球數(shù)據(jù)服務(wù)將Oracle RAC服務(wù)模型應(yīng)用于全球分布式數(shù)據(jù)庫池株茶，為一組提供公共服務(wù)的復(fù)制數(shù)據(jù)庫提供動態(tài)負載平衡来涨，故障轉(zhuǎn)移和集中式服務(wù)管理。該組數(shù)據(jù)庫可以包括Oracle RAC和通過Oracle Data Guard忌卤，Oracle GoldenGate或任何其他復(fù)制技術(shù)互連的單實例Oracle數(shù)據(jù)庫扫夜。
GDS與Oracle Data Guard代理集成。這允許在Oracle Data Guard代理配置中發(fā)生角色轉(zhuǎn)換時驰徊，適當(dāng)?shù)刈詣訂雍屯Ｖ固囟ㄓ诮巧娜址?wù)笤闯。
GDS允許規(guī)定全局服務(wù)的復(fù)制延遲限制。如果在給定副本處超過滯后限制棍厂，則全局服務(wù)在該副本處暫時停止颗味，并且新客戶端請求被路由到滿足滯后限制的副本。當(dāng)復(fù)制滯后變?yōu)樾∮跍笙拗茣r牺弹，全局服務(wù)將在原始副本上自動重新啟動浦马。
1.7 Summary of Oracle Data Guard Benefits
Oracle Data Guard offers these benefits:
■Disaster recovery, data protection, and high availability
Oracle Data Guard provides an efficient and comprehensive disaster recovery and high availability solution. Easy-to-manage switchover and failover capabilities allow role reversals between primary and standby databases, minimizing the downtime of the primary database for planned and unplanned outages.
■災(zāi)難恢復(fù)，數(shù)據(jù)保護和高可用性
Oracle Data Guard提供了一種高效张漂，全面的災(zāi)難恢復(fù)和高可用性解決方案晶默。 易于管理的切換和故障切換功能允許主數(shù)據(jù)庫和備用數(shù)據(jù)庫之間的角色顛倒，從而最大程度地減少計劃內(nèi)和計劃外中斷的主數(shù)據(jù)庫的停機時間航攒。
■Complete data protection
Oracle Data Guard can ensure zero data loss, even in the face of unforeseen disasters. A standby database provides a safeguard against unplanned outages of all types, including data corruption and administrative error. Because the redo data received from a primary database is validated at a standby database, physical corruptions that can occur at a primary database are not propagated to the standby database. Additional validation performed at a standby database also prevents logical intra-block corruptions and lost-write corruptions from propagating to the standby. Similarly, administrative errors such as accidental file deletions by a storage administrator are not propagated to a standby database. A physical standby database can also be used to protect against user errors either by delaying the redo apply or by using Flashback Database to rewind the standby and extract a good copy of the data.
Oracle Data Guard可以確保零數(shù)據(jù)丟失磺陡，即使面對不可預(yù)見的災(zāi)難。 備用數(shù)據(jù)庫提供了防止所有類型的計劃外中斷的保護措施漠畜，包括數(shù)據(jù)損壞和管理錯誤币他。 因為從主數(shù)據(jù)庫接收的重做數(shù)據(jù)在備用數(shù)據(jù)庫上進行驗證，所以可能發(fā)生在主數(shù)據(jù)庫中的物理損壞不會傳播到備用數(shù)據(jù)庫憔狞。 在備用數(shù)據(jù)庫上執(zhí)行的附加驗證還防止邏輯塊內(nèi)損壞和丟失寫入損壞傳播到備用數(shù)據(jù)庫蝴悉。 類似地，存儲管理員意外刪除文件等管理錯誤不會傳播到備用數(shù)據(jù)庫瘾敢。 物理備用數(shù)據(jù)庫還可用于通過延遲重做應(yīng)用或使用閃回數(shù)據(jù)庫來倒回備用數(shù)據(jù)庫并提取數(shù)據(jù)的良好副本來防止用戶錯誤拍冠。
Efficient use of system resources
The standby database tables that are updated with redo data received from the primary database can be used for other tasks such as backups, reporting, summations, and queries, thereby reducing the primary database workload necessary to perform these tasks, saving valuable CPU and I/O cycles.
使用從主數(shù)據(jù)庫接收的重做數(shù)據(jù)更新的備用數(shù)據(jù)庫表可用于其他任務(wù)，例如備份簇抵，報告庆杜，求和和查詢，從而減少執(zhí)行這些任務(wù)所需的主數(shù)據(jù)庫工作量正压，節(jié)省寶貴的CPU和I / O循環(huán)欣福。
Flexibility in data protection to balance availability against performance requirements
Oracle Data Guard offers maximum protection, maximum availability, and maximum performance modes to help enterprises balance data availability against system performance requirements.
在數(shù)據(jù)保護方面的靈活性责球，以便根據(jù)性能要求平衡可用性
Oracle Data Guard提供最大的保護焦履，最大可用性和最高性能模式拓劝，幫助企業(yè)根據(jù)系統(tǒng)性能要求平衡數(shù)據(jù)可用性。
■ Automatic gap detection and resolution
If connectivity is lost between the primary and one or more standby databases (for example, due to network problems), redo data being generated on the primary database cannot be sent to those standby databases. Once a connection is reestablished, the missing archived redo log files (referred to as a gap) are automatically detected by Oracle Data Guard, which then automatically transmits the missing archived redo log files to the standby databases. The standby databases are synchronized with the primary database, without manual intervention by the DBA.
■自動間隙檢測和處理
如果主數(shù)據(jù)庫和一個或多個備用數(shù)據(jù)庫之間的連接丟失（例如嘉裤，由于網(wǎng)絡(luò)問題）郑临，則無法將主數(shù)據(jù)庫上生成的重做數(shù)據(jù)發(fā)送到這些備用數(shù)據(jù)庫。 重新建立連接后屑宠，Oracle Data Guard會自動檢測丟失的歸檔重做日志文件（稱為差異）厢洞，然后自動將丟失的歸檔重做日志文件傳輸?shù)絺溆脭?shù)據(jù)庫。 備用數(shù)據(jù)庫與主數(shù)據(jù)庫同步典奉，無需DBA手動干預(yù)躺翻。
■Centralized and simple management
The Oracle Data Guard broker provides a graphical user interface and a command-line interface to automate management and operational tasks across multiple databases in an Oracle Data Guard configuration. The broker also monitors all of the systems within a single Oracle Data Guard configuration.
■集中，簡單的管理
Oracle Data Guard代理提供了圖形用戶界面和命令行界面卫玖，可在Oracle Data Guard配置中跨多個數(shù)據(jù)庫自動執(zhí)行管理和操作任務(wù)公你。 代理還監(jiān)視單個Oracle Data Guard配置中的所有系統(tǒng)。
■Integration with Oracle Database
Oracle Data Guard is a feature of Oracle Database Enterprise Edition and does not require separate installation.
■與Oracle數(shù)據(jù)庫集成
Oracle Data Guard是Oracle數(shù)據(jù)庫企業(yè)版的一項功能假瞬，不需要單獨安裝陕靠。
■Automatic role transitions
When fast-start failover is enabled, the Oracle Data Guard broker automatically fails over to a synchronized standby site in the event of a disaster at the primary site, requiring no intervention by the DBA. In addition, applications are automatically notified of the role transition.
■自動角色轉(zhuǎn)換
啟用快速啟動故障切換時，如果主站點發(fā)生災(zāi)難脱茉，Oracle Data Guard代理將自動故障轉(zhuǎn)移到同步備用站點剪芥，而不需要DBA的干預(yù)。 此外琴许，應(yīng)用程序會自動通知角色轉(zhuǎn)換税肪。
