Database backup includes fullbackup, differential backup and incremental backup. This name is given in terms of “what data to back up”.
full backup
The easiest and the basis of all backups is a full backup. It literally backs up all the data held by the system at one point in time. Therefore, with this backup file, it is possible to recover all the data at that time.
This is a story, but if it is always possible to take a full backup during an active backup, the backup operation will be extreamly simple. Because, as mentioned above, data recovery will end easily if it is this.
Disadvantages of full backup
Cost1: It takes a long time to backup
The backup takes a long time to back up all the data in the system. Although some reductions can be made by excluding data that does not change, such as read-only files, it is necessary to include them in the backup target, since the core business data is usually change daily.
Cost: The load on resources is large
The fact that the data to be backed up is large means that a large number of read operations occur on the disk where the data is stored during the backup. Therefore, backup processing consumes a large amount of resources, including disk and server CPUs, and, if backup is performed via a network, network connections. Threfore, parallel execution of other processes during backup is not a pratical operation. A full backup consumes the most resources of the backup.
Cost: need to stop service
In general, shut down the software such as DBMS and stop the service before acquiring a full backup. This is because you must obtain backups while maintaining data integrity. However, there are not many systems that can stop service frequently.
Differential backup
Differential backup, as the name suggests, is a method of backup only the changes from the previous full backup.
Using differential backup increases the recovery procedure by one, but instead reduces the time required for backup because the data requried for daily backup is smaller. The impact on resources is also reduced accordingly.
Incremental backup
The thrd backup method is incremental backup. This is a smart version of the differential backup without any waste. Earlier, with differential backup files, there were many files that were unnecessary for recovery. That is because the information contained in these files is the same. If this redundancy is eliminated, the data to be backuped up will be less and the backup time will be shorter.
