Backup and recovery

1. In information technology, a backup, or the process of backing up, refers to the copying and archiving of computer data so it may be used to restore the original after a data loss event. 

2. Backup is the activity of copying files or databases so that they will be preserved in case of equipment failure or other catastrophe. 

3. Backup is usually a routine part of the operation of large businesses with mainframes as well as the administrators of smaller business computers. For personal computer users, backup is also necessary but often neglected. The retrieval of files you backed up is called restoring them. 

4. Backup and recovery refers to the process of backing up data in case of a loss and setting up systems that allow that data recovery due to data loss. 

5. Backing up data requires copying and archiving computer data, so that it is accessible in case of data deletion or corruption. Data from an earlier time may only be recovered if it has been backed up. Data backup is a form of disaster recovery and should be part of any disaster recovery plan. Data backup cannot always restore all of a system's data and settings. For example, computer clusters, active directory servers, or database servers may need additional forms of disaster recovery because a backup and recovery may not be able to reconstitute them fully. 

6. Today, a great deal of data can be backed up when using cloud storage, which means archiving on a local system's hard drive or using external storage is not necessary. Mobile devices, in particular, can be set up using cloud technologies, allowing data to be recovered automatically.

Data Compression

Definition

The word 'compression' means 'reduction'.

Data compression is a process of encoding information applying some specific encoding scheme.

It is used for storing the data as well as for transmission.

When we receive the data it should be converted into its original form. Sometimes we may not be able to receive the original form of information after decodinng of compressed data, especially in case of pictures.

the goal of data compression is to store information source as accurately as possible using the fewest number of bits.

Need of data compression.

It is useful for reducing the compsumption of expensive resourses like hard disk space (Secondary Storage Devices) or transmission bandwidth.

The design of data compression schemes involves trade-offs among various facttors like the degree of compression, the amount of distortion introduced and the computational resources required to compress and uncompress the data.

To reduce the storage space.

To increase the capacity of the communication channel.

Information security - Data compression often changes the format of the original message. So it can be used for sensitive data to make it secure to some extent.

Backup

Most of the organizations maintain huge data with duplicate set known as backup.

Backup needs a huge storage space because after a certain period of time it needs to have  a copy of the original data. Data compression is also widely used in backup utilities.