Explain backup and recovery

 It is imperative to have a backup of the database in case the original is corrupted or lost because of any reason. Using this backup, the database can be recovered as it was before the failure.

Database backup basically means that a duplicate of the database information and data is created and stored in backup server just to be on the safe side. Transaction logs are also stored in the backup along with the database data because without them, the data would be useless.

1. Backup: Backup refers to storing a copy of original data which can be used in case of data loss. Backup is considered one of the approaches to data protection. Important data of the organization needs to be kept in backup efficiently for protecting valuable data. Backup can be achieved by storing a copy of the original data separately or in a database on storage devices. There are various types of backups are available like full backup, incremental backup, Local backup, mirror backup, etc. An example of a Backup can be SnapManager which makes a backup of everything in the database. 

2. Recovery: Recovery refers to restoring lost data by following some processes. Even if the data was backed up still lost so it can be recovered by using/implementing some recovery techniques. When a database fails due to any reason then there is a chance of data loss, so in that case recovery process helps in improve the reliability of the database. An example of Recover can be SnapManager which recovers the data from the last transaction. 

Reasons of Failure in a Database

There can be multiple reasons of failure in a database because of which a database backup and recovery plan is required. Some of these reasons are:

User Error -  Normally, user error is the biggest reason of data destruction or corruption in a database. To rectify the error, the database needs to be restored to the point in time before the error occured.

Hardware Failure -  This can also lead to loss of data in a database. The database is stored on multiple hard drives across various locations. These hard drives may sometimes malfunction leading to database corruption. So, it is important to periodically change them.

Catastrophic Event -  A catastrophic event can be a natural calamity like a flood or earthquake or deliberate sabotage such as hacking of the database. Either way, the database data may be corrupted and backup may be required.

Methods of Backup

The different methods of backup in a database are:

Full Backup -  This method takes a lot of time as the full copy of the database is made including the data and the transaction records.

Transaction Log -  Only the transaction logs are saved as the backup in this method. To keep the backup file as small as possible, the previous transaction log details are deleted once a new backup record is made.

Differential Backup -  This is similar to full backup in that it stores both the data and the transaction records. However only that information is saved in the backup that has changed since the last full backup. Because of this, differential backup leads to smaller files.

Database Recovery

There are two methods that are primarily used for database recovery. These are:

Log based recovery -  In log based recovery, logs of all database transactions are stored in a secure area so that in case of a system failure, the database can recover the data. All log information, such as the time of the transaction, its data etc. should be stored before the transaction is executed.

Shadow paging -  In shadow paging, after the transaction is completed its data is automatically stored for safekeeping. So, if the system crashes in the middle of a transaction, changes made by it will not be reflected in the database.

Backup and recovery are critical processes in information technology (IT) that involve creating copies of data and ensuring that these copies can be restored in the event of data loss or corruption. These processes are designed to protect against a wide range of potential threats, including hardware failures, software errors, malware attacks, natural disasters, and human error.

Backup refers to the process of creating copies of data and storing them in a separate location or device. This can be done manually or automatically, depending on the specific backup strategy. The primary goal of backup is to provide a safe and secure copy of data that can be used to restore information in the event of data loss or corruption.

Recovery refers to the process of restoring data from a backup. The recovery process involves identifying the data that needs to be restored, retrieving the backup copy of that data, and transferring it back to its original location. The speed and effectiveness of the recovery process depend on the quality of the backup strategy, the speed of the backup device, and the amount of data that needs to be restored.

There are different types of backup strategies, including full backups, incremental backups, and differential backups. A full backup involves copying all data to a backup device, while an incremental backup only copies data that has changed since the last backup. A differential backup, on the other hand, copies all data that has changed since the last full backup.

The choice of backup strategy depends on various factors, including the size of the data to be backed up, the frequency of changes to the data, and the available backup resources. It is essential to regularly test the backup and recovery process to ensure that it works as expected and to identify any potential issues or gaps in the backup strategy.

People Also Find for:

1. What is data backup and recovery?
2. What Is Backup and Recovery?
3. What are backup and disaster recovery?