Understand Variety of Backup Options in SQL Server

Andrew Jackson | Published: March 11, 2019 | Backup, SQL |

SQL Server is a relational database management system, which can be used by many organisations to keep sensitive data secure. Further, it provides many options for making backups in SQL Server. Now, in the upcoming section, we will learn various backup options in SQL Server. Read the below section without wasting any time.

Here’s Multiple Backup Options in SQL Server

There are different types of backups available in SQL Server and some of them are listed below:

Full Backups

The most common backup types are complete or full backups, also called database backups. These backups will create a complete backup of the database and also a part of the transaction log, thus, the database files can be restored. This will allow the simplest form of SQL database restoration, as all contents are contained in a single backup.

A full backup should be finished at least once before any other types of backups can be run—this is the basic foundation for the backup of any kind.

Differential Backups

The differential backup is just a super-set of last full backup and includes all changes that have been made since the most recent full backup. So, if there are some transactions that recently happened, a full or differential backup could be small in size, but if you have made a large number of transactions, the differential backup could be very large in size.

Since the differential backup does not back up everything, the backup normally runs quicker as compared to full backup. A differential backup represents the state of changed extents at time the backup was created. If you generate the series of differential backups, frequently-updated databases are likely to contain multiple data in every differential. As the differential database backups increase in size, retrieving the differential backup can significantly expand the time that is involved to restore the database. Thereby, it is always recommended to take a full backup, at sets of intervals, to start a new differential base for data.

Transaction Log Backup

A log backup, as the name suggests, backing up the transaction log. This backup type is only potential with full and bulk-logged recovery models. A transaction log file can store the series of logs that may provide history of every changed data, in a database. The T-log (transaction log) backup contains each log record that’s never been involved in last transaction log backups.

It permits the database to be restored to a certain point of time. It simply means that transaction log backups are differential and incremental and both are cumulative in nature. In case, if you want to recover the database to a particular point in time, you have to recover a full, recent differential, and all the transaction logs that are necessary to make the database up to a certain point, or to a point close to the desired target point in time, prior to the occurrence of accident that may result in data loss. A series of modification is contained and retained by using LSN (Log Sequence Number) in the log chain. A backup log chain is unbroken series of logs that consist of all transaction records needed to recover a database to a certain point in time. At all times, a log chain starts with a complete or full database backup and continues until the reason it breaks chain (Let’s suppose, changing the database recovery model to simple, or taking the extra full backup), thus by preventing a log backup from being taken on a database until another full or differential backup can be initiated for that database.

List of Some Additional Backup Options in SQL Server

File Backups

Another option for backing up databases is to use “File” backups. It allows to backup each file separately instead of having the whole database backup. This is relevant if you must have created more than one data files for any database. Only a single reason for this type of backup is if you have too large files and need to get them back individually. File backups of a read-only file-group can be tied to partial backups.

Partial Backups

Partial backup is the least-used backup method available in the SQL Server. All the database recovery models can support all partial backups, but a partial backup is widely used in simple recovery model to improve the flexibility when backing up big databases that consist read-only file-groups.

Copy-only Backups

A copy-only backup is the special type of a full backup and it is independent of the sequence of conventional backups. The difference between two backups, i.e., copy-only and a full backup that means a copy-only backup cannot be a base for next differential backups. A full backup works with different database recovery models. Otherwise, a copy-only backup is only applicable for full or bulk-logged recovery models. A copy-only backup restoration is not so different from a normal restoration process.

File Group Backups

Additionally, to do ‘File’ backups you can also do ‘File-group’ backups that allows to create backup of each file that are present in a specific file-group. By default every database contains a PRIMARY file-group which is connected to a single data file that is already created. Also, you have option to create additional file-groups and then place a new data file in any file-group. In many cases you will probably have a PRIMARY file-group, thus this is not relevant.

Conclusion

As we all know, SQL Server backups is a very vast subject itself. There are many options provided by SQL Server to create backups in SQL Server. Thus, in the above section, we have discussed all SQL Server backup options. Moreover, we have covered some additional options for backing up the SQL Server database.