IBM 000-8697 User Manual

System Architecture

In this guide, system architecture is interpreted broadly to include OnLine
database server processes as well as OnLine shared memory and disk data
structures. This chapter provides optional reference material about OnLine 5.x
operation that is intended to deepen your understanding. Topics in other
chapters contain cross-references to specific topics in this chapter if
additional information could prove helpful for understanding.

OnLine system architecture can be separated into two major categories:

■

Shared memory

■

Disk data structures

The first half of this chapter covers shared-memory topics. The second half of
this chapter, which begins on

, describes information related to the

disk data structures.

OnLine initialization refers to two related activities: shared-memory initial-
ization and disk-space initialization. To initialize OnLine, you execute the
tbinit

 process. You can do this directly from the

UNIX

 command line or

indirectly via

DB-M

onitor. The options you include in the tbinit command or

the option you select from

DB-M

onitor determines the specific initialization

procedure that tbinit executes.

Refer to

for a detailed description of what happens during shared-

memory initialization.

Refer to

 for a detailed description of what happens during disk-

space initialization.