IBM 000-8697 User Manual

System Architecture

Daemon processes are OnLine user processes that perform system-wide
tasks. Unlike database server processes, a daemon process is not associated
with a corresponding application development tool process.

The OnLine system employs three different types of daemons, which are
listed below.

■

, the master daemon

■

, the undertaker daemon

■

, a page-cleaner daemon

Daemon processes are identified in tbstat -u output by a

D

 (daemon) flag or

an

F

 (page cleaner or “flusher”) flag in the fourth flag position of the user

entry.

The tbinit daemon is spawned by the tbinit process early in the initialization
process. The tbinit daemon occupies the first entry in the shared-memory
user table, which is represented by the first entry in tbstat -u output.

The tbinit daemon is responsible for most of the tasks of disk space and
shared-memory initialization. (Refer to

The tbinit daemon also schedules the work of the page-cleaner daemons. If
no page-cleaner daemons exist, tbinit takes over page-cleaning responsibil-
ities. (Refer to

 for a detailed explanation of buffer page flushing,

which is the responsibility of the page-cleaner daemons.)