Database server initialization

The database server requires both disk-space initialization and shared-memory initialization.

Shared-memory initialization

Shared-memory initialization, or starting the server, establishes the contents of database server shared memory as follows: internal tables, buffers, and the shared-memory communication area. Shared memory is initialized every time the database server starts. You use the oninit utility from the command line to initialize database server shared memory and bring the database server online.

Disk-space initialization

Disk-space initialization uses the values that are stored in the configuration file to create the initial chunk of the root dbspace on disk. You use the oninit -i command from the command line to initialize disk space. When you initialize disk space, the database server automatically initializes shared memory as part of the process. Disk space is initialized the first time the database server starts.

Warning: When you initialize disk space, you overwrite whatever is on that disk space. If you reinitialize disk space for an existing database server, all the data in the earlier database server is deleted.

You can prevent accidental disk initialization by setting the FULL_DISK_INIT configuration parameter to 0. When this configuration parameter is set to 0, the oninit -i command fails if the root dbspace exists.

The key difference between shared-memory initialization and disk-space initialization is that shared-memory initialization has no effect on disk-space allocation or layout. No data is deleted.