Difference between: Full, Differential, and Incremental Backup

Difference between: Full, Differential, and Incremental Backup

Submitted by Backup on Mon, 01 Aug 2011 - 12:23.

Type	Definition	Benefits	Drawbacks
Full Backup:	A complete backup of everything you want to backup.	Restoration is fast, since you only need one set of backup data.	The backing up process is slow. High storage requirements.
Differential Backup:	The backup software looks at which files have changed since you last did a full backup. Then creates copies of all the files that are different from the ones in the full backup. If you do a differential backup more than once, it will copy all the files, or parts of files that have changed since the last full backup, even if you already have identical copies of those files in a previous differential backup. For restoring all the data, you will only need the the last full backup, and the last differential backup.	Faster to create than a full backup. Restoration is faster than using incremental backup. Not as much storage needed as in a full backup.	Restoration is slower than using a full backup. Creating a differential backup is slower than creating an incremental backup.
Incremental Backup:	The backup software creates copies of all the files, or parts of files that have changed since previous backups of any type (full, differential or incremental). For example if you did a full backup on Sunday. An incremental backup made on Monday, would only contain files changed since Sunday, and an incremental backup on Tuesday, would only contain files changed since Monday, and so on.	This method is the fastest when creating a backup. The least storage space is needed.	Restoring from incremental backups is the slowest because it may require several sets of data to fully restore all the data. For example if you had a full backup and six incremental backups. To restore the data would require you to process the full backup and all six incremental backups.

    

 

Oracle - What are different types of backup?

What are different types of backup? (Hot, Cold, logical, Physical)? 

Cold BackupIn this type of backup, after the database is shut down, DBA exits the SVRMGR utility and copies the log files, data files and control files onto a backup media.Once the backup has been completed the DBA can restart the database.
Physical Backup 
The operating system saves the database files onto tape or some other media. This is useful to restire the system to an earlier point whenever needed.Logical Backup In logical backup technique, the IMPORT/EXPORT utilities are used to create the backup of the database. A logical backup backs-up the contents of the database. A logical backup can be used to restore the database to the last backup. However, unlike physical back, it should not be used to create an OS back up copy because restoring using this approach would make it possible to correct the damaged datafiles. Therefoe in these situations physical backups should be preferred.Hot backup A few systems that need to support continuous operation, it is difficult to bring down the database without interrupting the service provided to the users. In such cases, hot backup approach should be used.
There are two modes in which the hot backup works:
ARCHIEVELOG mode
NOARCHIVELOG mode
The database operations are suspended until archiving has been completed if the on-line redo log files are filled before they can be archived.
It is important that the directory containing the archived log files doesnt become full because if it does the ARCH thread wouldnt be able to archive the redo log files. The DBA has to continuously monitor the used-space percentage in the archive directory.
The database can be placed into ARCHIVELOG mode at the creation time or after the database has been created.
However, the database is shutdown before connecting as the user INTERNAL.
It was originally created in NOARCHIVELOG mode, this technique can be used to place the database in ARCHIVELOG mode 

 

Thanks

Srini