Database Server Operating Modes

You can determine the current database server mode by executing the onstat utility from the command line. The onstat header displays the mode.

The database server has three principal modes of operation, as Table 9 illustrates.

Table 9. Operating Modes
Operating Mode	Description
Offline mode	When the database server is not running. No shared memory is allocated.
Quiescent, or administration, mode	When the database server processes are running and shared-memory resources are allocated, but the system does not allow database user access. Only the administrator (user informix) can access the database server.
Online mode	Users can connect with the database server and perform all database activities. This is the normal operating mode of the database server. User informix or user root can use the command-line utilities to change many database server ONCONFIG parameter values while the database server is online.
Microkernel mode	Users can perform a cold restore with the database server in microkernel mode. For more information about cold restore, refer to the IBM Informix: Backup and Restore Guide.

In addition, the database server can also be in one of the following modes:

Read-only mode is used by the secondary database server in a high-availability data-replication pair. An application can query a database server that is in read-only mode, but the application cannot write to a read-only database.
Recovery mode is transitory. It occurs when the database server performs fast recovery or recovers from a system archive or system restore. Recovery occurs during the change from Offline to Quiescent mode.
Shutdown mode is transitory. It occurs when the database server is moving from online to quiescent mode or from online (or quiescent) to offline mode. Current users access the system, but no new users are allowed access.
Once shutdown mode is initiated, it cannot be cancelled.