Creating a Multifile Shadow (Using CREATE SHADOW)

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You can create multifile shadows, similarly to the way you create multifile databases. To create a multifile shadow, specify the name and size of each file in the shadow set. File specifications are platform-specific.

The following examples illustrate the creation of a multifile shadow on a UNIX platform. They create the shadow files on the A, B, and C drives of the IB_bckup node.

The first example creates a shadow set consisting of three files. The primary file, employee.shd, is 10,000 database pages in length and the first secondary file is 20,000 database pages long. The final secondary file, as always, grows as needed.

CREATE SHADOW 1 'D:/shadows/employee.shd' LENGTH 10000
FILE 'D:/shadows/employee2.shd' LENGTH 5000
FILE 'D:/shadows/employee3.shd';

Instead of specifying the page length of secondary files, you can specify their starting pages. The previous example could be entered as follows:

CREATE SHADOW 1 'D:/shadows/employee.shd' LENGTH 10000
FILE 'D:/shadows/employee2.shd' STARTING AT 10000
FILE 'D:/shadows/employee3.shd' STARTING AT 30000;

In either case, you can use SHOW DATABASE to verify the file names, page lengths, and starting pages for the shadow just created:

SHOW DATABASE;
Database: employee.ib
Owner: SYSDBA
Shadow 1: "D:\SHADOWS\EMPLOYEE.SHD" auto length 10000
file D:\SHADOWS\EMPLOYEE2.SHD starting 10000
file D:\SHADOWS\EMPLOYEE3.SHD starting 30000
PAGE_SIZE 1024
Number of DB pages allocated = 462
Sweep interval = 20000

Note

The page length allocated for secondary shadow files need not correspond to the page length of the database’s secondary files. As the database grows and its first shadow file becomes full, updates to the database automatically overflow into the next shadow file.