Recovery database

Bài giảng Cơ sở dữ liệu nâng cao - Chapter 2: Disaster recovery. Chương này trình bày một số nội dung sau: Overview about database backup and recovery, backup & restore strategy, disaster recovery planning,... Mời các bạn cùng tham khảo.

18p nomoney10 05-04-2017 68 8   Download

Bài giảng Kiến trúc cài đặt cơ sở dữ liệu - Chương 3: Sao lưu và khôi phục dữ liệu (Backup and recovery). Những nội dung chính được trình bày trong chương này gồm có: Mô hình recovery, chiến lược backup, chiến lược restore. Mời các bạn cùng tham khảo.

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Upon completion of this lesson, the successful participant will be able to: Understand the need for and importance of database administration; learn different ways of processing a database; understand the need for concurrency control, security, and backup and recovery; learn typical problems that can occur when multiple users process a database concurrently; understand the use of locking and the problem of deadlock;…

62p tangtuy17 11-07-2016 40 2   Download

Tìm hiểu về Mailbox Recovery Exchange 2010 .Trong một số phiên bản trước của Exchange Server, chúng ta có thể sử dụng tính năng Recovery Storage Group – RSG, cho phép người sử dụng lưu trữ bản copy của file EDB của Mailbox Database, đồng thời có thể dễ dàng khôi phục từng thành phần mailbox riêng rẽ hoặc một số yếu tố có liên quan khác như mail, calendar hoặc contact.

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Using Online Redo Log Files Online redo log files provide the means to redo transactions in the event of a database failure. Every transaction is written synchronously to the Redo Log Buffer, then gets flushed to the online redo log files in order to provide a recovery mechanism in case of media failure. (With exceptions such as direct load inserts in objects with the NOLOGGING clause enabled.) This includes transactions that have not yet been committed, undo segment information, and schema and object management statements.

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Overview The recovery catalog is a schema that is created in a separate database. It contains the RMAN metadata obtained from the target database control file. RMAN propagates information about the database structure, archived redo logs, backup sets, and datafile copies into the recovery catalog from the control file of the target database. You should use a catalog when you have multiple target databases to manage. RMAN stores, uses, and maintains the information in the recovery catalog. The recovery catalog is maintained by RMAN when you do the following: 1.

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Workshop Methodology Group-Oriented and Interactive Structure The workshop is structured to allow individuals to work in groups to perform database backup, restore, and recovery operations. Each group is encouraged to share its approach to resolving database failures with other groups in the class. Intensive Hands-On Diagnosis and Problem Resolution The intent is to provide you with as much hands-on experience as possible to diagnose and work through backup and recovery scenarios.

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Incomplete Recovery Incomplete recovery reconstructs the database to a prior point in time (before the time of the failure). Note: This situation results in the loss of data from transactions committed after the time of recovery. This data will need to be reentered manually if required. Perform this recovery only when absolutely necessary. Incomplete recovery can be a difficult and time-consuming operation.

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Using Oracle Enterprise Manager You can use the Recovery Wizard to restore and recover your database. On the Range Selection page you must enter a date and time to restore to a previous point. You use Instance Management or the Console to open the database after the job has completed. You can view the status of the job by selecting the Active and History page tabs in the Console’s Job window.

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Restoration and Datafile Media Recovery Using RMAN RMAN automates the procedure for restoring files. When you issue the RESTORE command, RMAN uses a server session to restore the correct backups and copies. The RMAN repository is used to select the best available backup set or image copies to use in the restoration. By default, RMAN does not restore a file if the file is already in the correct place and its header contains the correct information. In releases before Oracle9i, the files were always restored.

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Media Recovery Media recovery is used to recover a lost or damaged current datafile or control file. You can also use it to recover changes that were lost when a datafile went offline without the OFFLINE NORMAL option. Restoring Files When you restore a file, you are replacing a missing or damaged file with a backup copy. Recovery of Files When you recover a file, changes recorded in the redo log files are applied to the restored files.

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Types of Recovery Manager Backups Recovery Manager provides functionality to back up: The entire database, every datafile in a tablespace, or a single datafile The control file All or selected archived logs Note: The online redo log files are not backed up when using Recovery Manager. Closed Database Backups A closed database backup is defined as a backup of the database while it is closed (offline). This is the same as the consistent database backup. If you are performing a closed backup, the target database must not be open.

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Backup Terminology Whole Database Backup Whole database backup (also known as whole backup) refers to a backup of all datafiles and the control file of the database. Whole backups can be performed when the database is closed or open. This is the most common method of backup. The whole backup that is taken when the database is closed (after the database is shut down using the NORMAL, IMMEDIATE, or TRANSACTIONAL options) is called a consistent backup.

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Recovery Manager Features Recovery Manager (RMAN) is an Oracle utility that you use to manage the backup, restore, and recovery operations on Oracle databases. RMAN has a powerful command language that is independent of the operating system. Recovery Manager has a command-line interface. Oracle Enterprise Manager also provides a graphical user interface for the Recovery Manager. Recovery Manager can be used on databases of Oracle8 or later releases. RMAN provides several features not available when you make user-managed backups with operating system commands.

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Overview The Oracle server uses many memory components, background processes, and file structures for its backup and recovery mechanism. This lesson reviews the concepts presented in the Oracle9i Database Administration Fundamentals I course, with an emphasis on backup and recovery requirements. Oracle Instance An Oracle instance consists of memory areas (mainly System Global Area [SGA]) and background processes, namely PMON, SMON, DBWn, LGWR, and CKPT. An instance is created during the nomount stage of the database startup after the parameter file has been read.

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Redo Log History All transactions are recorded in the online redo log files. This allows for automatic recovery of transactions in the event of a database failure. If the database is configured for NOARCHIVELOG mode, no redo history is saved to archived log files, and recovery operations are limited and a loss of transaction work may occur. This is the result of the automatic recycling of log files, where older log files needed for recovery are overwritten and only the most recent part of the transaction history is available.

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Overview One of the major responsibilities of a database administrator (DBA) is to ensure that the database is available for use. The DBA can take precautions to minimize failure of the system. In spite of the precautions, it is naive to think that failures will never occur. The DBA must make the database operational as quickly as possible in case of a failure and minimize the loss of data. To protect the data from the various types of failures that can occur, the DBA must back up the database regularly. Without a current backup, it is impossible for the DBA to...

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In either case, the easiest way is to drop the entire tablespace that contains the datafile. The steps that are to be executed from within SQL*Plus are: 1. STARTUP MOUNT 2. For each deleted datafile, issue the command ALTER DATABASE DATAFILE ’full path of filename’ OFFLINE [DROP]; Note: You must use the DROP option if the database is in NOARCHIVELOG mode, because you cannot recover this file if you apply incomplete media recovery on it via the command ALTER DATABASE OPEN RESETLOGS. See the SQL Reference for details. 3. ALTER DATABASE OPEN; 4.

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Quản Trị Mạng - Trong một số phiên bản trước của Exchange Server, chúng ta có thể sử dụng tính năng Recovery Storage Group – RSG, cho phép người sử dụng lưu trữ bản copy của file EDB của Mailbox Database, đồng thời có thể dễ dàng khôi phục từng thành phần mailbox riêng rẽ hoặc một số yếu tố có liên quan khác như mail, calendar hoặc contact. Còn trong Exchange 2010, chúng ta không thể sử dụng Storage Groups, và do vậy cũng không còn tính năng Recovery Storage Group, và thay vào đó là Recovery Database, nhưng...

8p abcdef_43 03-11-2011 86 15   Download

Hệ thống Mail server của bạn đang hoạt động và bạn cũng có kế hoạch backup mailbox database định kỳ. Vì một lý do gì đó Mailbox database bị lỗi hay Mailbox server không làm việc. Toàn bộ hệ thống mail bị tê liệt, bạn phải restore mailbox database lại. Nhưng công việc này tốn khá nhiều thời gian, ảnh hưởng đến việc gửi và nhận mail của user, làm cho nhu cầu liên lạc e-mail của công ty bị gián đoạn trong......

26p hoangtumayman 27-06-2011 88 16   Download