Structure of the Root Dbspace

The ROOTNAME, ROOTOFFSET, ROOTPATH, and ROOTSIZE configuration parameters specify the size and location of the initial chunk of the root dbspace. If the root dbspace is mirrored, the MIRROROFFSET and MIRRORPATH configuration parameters specify the mirror-chunk location. For more information about these parameters, see Configuration Parameters.

As part of disk-space initialization, the database server initializes the following structures in the initial chunk of the root dbspace:

• Fourteen reserved pages
• The first chunk free-list page
• The tblspace tblspace
• The database tblspace
• The physical log
• The logical-log files
• The safewrite area

To check that your root dbspace follows this organization, execute the following command, which produces a dbspace usage report by chunk:

• onutil CHECK SPACE DISPLAY

  For more information, see CHECK SPACE.

Reserved Pages

The first 14 pages of the initial chunk of the root dbspace are reserved pages. Each reserved page contains specific control and tracking information used by the database server.

To obtain a listing of the contents of your reserved pages, execute the command onutil CHECK RESERVED DISPLAY.

Safewrite Area

The safewrite area is used to store information about the configuration of coservers within Extended Parallel Server. The safewrite area is stored on coserver 1. The CONFIGSIZE parameter determines the size of the safewrite area. For information about how to configure the safewrite area, refer to CONFIGSIZE.