12.2 Backup Sets

12.2 Backup Sets

12.2.1 Backup Set

A single backup is called a backup set.
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The backup engine generates a header for each backup set so that you can quickly query for any backup sets contained in that media set at a later time.

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12.2.2 Options for backup sets

(1) Name
Specifies the backup set name. The system automatically suggests a default name based on the database name and backup type.
T-SQL Example: with NAME = N ' sqldb01-full database backup '

(2) Description
A brief description of the backup set.
T-SQL Example: with DESCRIPTION = N ' Full backup '

(3) Backup set expiration time
You can specify how many days to expire, or specify expiration after a specific date, so that the space occupied by the backup set can be reused. Note: Only one of these two parameters can be selected.
"Later Than (days)" Specifies the number of days after which the backup set expires and can be overwritten. This value range is 0-99,999 days, and 0 days indicates that the backup set will never expire.
T-SQL Example: with retaindays = 14
On (a specific date) specifies the date on which the backup set expires and can be overwritten.
T-SQL Example: with expiredate = N ' 2013-10-31 '

12.2.3 Header Information

Each backup generates 2 headers.
(1) The header of the media set
The header of the media set identifies which media set this media belongs to, as well as information such as the date of writing.

(2) The header of the backup set
The backup engine will number each backup set on the backup media. The header of the backup set contains this number information, along with other necessary information such as backup type (full backup, differential backup, etc.), backup start time, backup stop time, and so on.

This article is from the "SQL Server Administrator's Guide" blog, declined reprint!

12.2 Backup Sets