Single-User Mode

This feature reduces the risk of sessions of users who are not user informix interfering with maintenance or migration tasks of the database server administrator. In Version 8.50 and earlier releases, Extended Parallel Server has two modes that can support operations on a database:

• On-line mode, in which multiple users can perform DDL and DML operations
• Quiescent mode, in which the onutil utility can check and repair certain RSAM data structures

This feature adds a new single-user mode, in which only user informix can perform and log database operations. Switching the database server to single-user mode from on-line mode aborts all sessions of users who are not informix, and rolls back their open transactions.

A new -j command-line option to the oninit and onmode utilities respectively start up or switch the database server into single-user mode.

Conversion to and reversion from XPS 8.51 require the server instance to be in single-user mode. During conversion to XPS 8.51, the database server remains in single-user mode after conversion has completed, until the Database Server Administrator switches to another mode.

Migration to XPS 8.51 is supported from the following earlier versions:

• 8.40.UD1
• 8.40.FD1
• 8.50.UC2
• 8.50.FC2

Reversion from XPS 8.51 is also supported to those earlier versions.

For more information about switching to or from single-user mode, or starting the database server in single-user mode, see Switching to or Starting the Server in Single-User Mode.