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Database Administration
Protecting Your Data : After-imaging : Creating after-image areas
 

Creating after-image areas

You create after-image areas using PROSTRCT and a structure description file. Use PROSTRCT CREATE to create after-image areas when you first define your database, and PROSTRCT ADD to add after-image areas to an existing database.
To create AI areas when defining your database:
1. Create the structure description file for the database. See Creating and Deleting Databases for a complete description of how to create a structure description file.
a. Define the data extents.
b. Define any BI extents.
c. Define any fixed-length AI extents. You must define four tokens in the file description line.
The table below describes each token and value you enter for fixed-length files.
Table 27. File tokens
Token
Description
Storage area type
Specifies the file type. Type a to indicate that this extent is an AI extent.
Extent path and file name
Specifies the extent file pathname. Enter a pathname that represents a standard operating system file. If you do not supply an extension, the database engine automatically appends a .a extension.
Extent type
Specifies whether the extent is a fixed-length or variable-length extent. Type f for a fixed-length extent. It must be lowercase.
Extent size
Specifies the length of the extent in 1,024-byte (1K) units. The minimum length for a fixed-length extent is 16K. The extent length must be a multiple of 16K for all operating systems. If you specify any other size, PROSTRCT displays a warning message and rounds the size up to the next multiple of 16K. The maximum length of an extent depends on the size of the file system and/or physical volume that contains the extent.
The following example shows a fixed-length after-image extent definition:
a db/mary/apdir/test.a1 f 2048
d. Define any variable-length after-image extents. Only specify the first two tokens: the extent type and pathname. Unlike data or BI extents, you can define more than one variable-length after-image extent for a database.
2. Create the empty database structure using the PROSTRCT utility. For more information about the structure description file and PROSTRCT, see Maintaining Database Structure.
3. Create the initial database contents using the PROCOPY or PROREST utility. For more information about the PROCOPY and PROREST utilities, see Other Database Administration Utilities
* Adding AI areas to an existing database