Database Backup And Recovery Pdf

database backup and recovery pdf

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Published: 27.04.2021

The physical structures of the database and the role each plays in the database recovery process determine the forms of backup and recovery available through user-managed techniques and through RMAN. The files and other structures that make up an Oracle database store data and safeguard it against possible failures.

Managing enterprise data backups and being prepared for disaster recovery scenarios across desktops, laptops, on-prem servers, virtual servers and the public cloud can easily become an overwhelming job. Keeping up with data growth using tape libraries and secondary storage sites poses a scalability challenge that has organizations looking to cloud storage for a simpler, faster way to back up their growing digital assets. You need a way to keep your business running in the unfortunate event of an outage or if data should otherwise get lost or corrupted. But backups now consume more storage than ever. Data is growing exponentially, even doubling every year in some industries.

Solving your database backup and recovery problems with Commvault

Database Backup Database Backup is storage of data that means the copy of the data. It is a safeguard against unexpected data loss and application errors. It protects the database against data loss. If the original data is lost, then using the backup it can reconstructed. The backups are divided into two types, 1. Physical Backup 2. Logical Backup 1. Physical backups Physical Backups are the backups of the physical files used in storing and recovering your database, such as datafiles, control files and archived redo logs, log files.

It is a copy of files storing database information to some other location, such as disk, some offline storage like magnetic tape. Physical backups are the foundation of the recovery mechanism in the database. Physical backup provides the minute details about the transaction and modification to the database. Logical backup Logical Backup contains logical data which is extracted from a database.

It includes backup of logical data like views, procedures, functions, tables, etc. Importance of Backups Planning and testing backup helps against failure of media, operating system, software and any other kind of failures that cause a serious data crash. It determines the speed and success of the recovery. Physical backup extracts data from physical storage usually from disk to tape. Operating system is an example of physical backup. Logical backup extracts data using SQL from the database and store it in a binary file.

Logical backup is used to restore the database objects into the database. So the logical backup utilities allow DBA Database Administrator to back up and recover selected objects within the database.

Storage of Data Data storage is the memory structure in the system. The storage of data is divided into three categories: 1. Volatile Memory 2. Non — Volatile Memory 3. Stable Memory 1. Volatile Memory Volatile memory can store only a small amount of data. For eg. Main memory, cache memory etc. Volatile memory is the primary memory device in the system and placed along with the CPU. In volatile memory, if the system crashes, then the data will be lost.

RAM is a primary storage device which stores a disk buffer, active logs and other related data of a database. Primary memory is always faster than secondary memory. When we fire a query, the database fetches a data from the primary memory and then moves to the secondary memory to fetch the record. If the primary memory crashes, then the whole data in the primary memory is lost and cannot be recovered. To avoid data loss, create a copy of primary memory in the database with all the logs and buffers, create checkpoints at several places so the data is copied to the database.

Non — Volatile Memory Non — volatile memory is the secondary memory. These memories are huge in size, but slow in processing. Flash memory, hard disk, magnetic tapes etc. If the secondary memory crashes, whole data in the primary memory is lost and cannot be recovered. To avoid data loss in the secondary memory, there are three methods used to back it up : 1. Remote backup creates a database copy and stores it in the remote network.

The database is updated with the current database and sync with data and other details. The remote backup is also called as an offline backup because it can be updated manually.

If the current database fails, then the system automatically switches to the remote database and starts functioning. The user will not know that there was a failure. The database is copied to secondary memory devices like Flash memory, hard disk, magnetic tapes, etc. If the system crashes or any failure occurs, the data would be copied from these tapes to bring the database up. The huge amount of data is an overhead to backup the whole database.

To overcome this problem the log files are backed up at regular intervals. The log file includes all the information about the transaction being made. These files are backed up at regular intervals and the database is backed up once in a week. Stable Memory Stable memory is the third form of the memory structure and same as non-volatile memory.

In stable memory, copies of the same non — volatile memories are stored in different places, because if the system crashes and data loss occurs, the data can be recovered from other copies. Causes of Database Failures A database includes a huge amount of data and transaction. If the system crashes or failure occurs, then it is very difficult to recover the database.

There are some common causes of failures such as, 1. System Crash 2. Transaction Failure 3. Network Failure 4. Disk Failure 5. If we fail to maintain the ACID properties, it is the failure of the database system. System Crash System crash occurs when there is a hardware or software failure or external factors like a power failure. The data in the secondary memory is not affected when system crashes because the database has lots of integrity. Checkpoint prevents the loss of data from secondary memory.

Transaction Failure The transaction failure is affected on only few tables or processes because of logical errors in the code. This failure occurs when there are system errors like deadlock or unavailability of system resources to execute the transaction. Network Failure A network failure occurs when a client — server configuration or distributed database system are connected by communication networks.

Disk Failure Disk Failure occurs when there are issues with hard disks like formation of bad sectors, disk head crash, unavailability of disk etc. Media Failure Media failure is the most dangerous failure because, it takes more time to recover than any other kind of failures.

A disk controller or disk head crash is a typical example of media failure. Natural disasters like floods, earthquakes, power failures, etc.

Database Recovery.

Database Backup and Recovery

In information technology , a backup , or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is " back up ", whereas the noun and adjective form is " backup ". A backup system contains at least one copy of all data considered worth saving. The data storage requirements can be large. An information repository model may be used to provide structure to this storage.

Accelerate recovery, increase performance, and easily migrate data to the cloud. With the wide array of databases currently deployed in the market, you need a unified approach to protecting and managing the entire database environment that enables you to migrate workloads to the cloud faster, backup your databases more efficiently, and streamline data access, all while supporting copy data management capabilities. Commvault aids you in overcoming these challenges, with a comprehensive approach to database backup and recovery that provides you the following benefits:. Enterprise support for cloud solutions. You can automatically create virtual machine compute instances with all the appropriate resources, including storage and software, as part of a single migration workflow to accelerate your move to the cloud. Because data can be migrated directly to these virtual instances, the cloud becomes an extension of your physical data center — helping you cut storage and data management costs. Database management.

Database Backup. Database systems, like any other computer system, are subject to failures but the data stored in it must be available as and when required. When a database fails it must possess the facilities for fast recovery. It is a safeguard against unexpected data loss and application errors. To rectify the error, the database needs to be restored to the point in time before the error occured.

Database Backup Strategies

Database Backup Database Backup is storage of data that means the copy of the data. It is a safeguard against unexpected data loss and application errors. It protects the database against data loss. If the original data is lost, then using the backup it can reconstructed.

A single view for managing your entire environment

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Database Backup and Recovery

А еще считаюсь лингвистом. Он не мог понять, как до него не дошло. Росио - одно из самых популярных женских имен в Испании. В нем заключено все, что ассоциируется с представлением о молодой католичке: чистота, невинность, природная красота. Чистота заключена в буквальном значении имени - Капля Росы.

 - А тебе здесь делать нечего. Беккер повернулся, печально посмотрев в последний раз на ее руку. Ты ничего не можешь с этим поделать, Дэвид.

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Стратмор был уверен, что предусмотрел .


Aniketa S.


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