Database Reference
In-Depth Information
There are two classes of background processes: those that have a focused job to do (as just described) and those
that do a variety of other jobs (i.e., utility processes). For example, there is a utility background process for the internal
job queues accessible via the
DBMS_JOB/DBMS_SCHEDULER
packages. This process monitors the job queues and runs
whatever is inside them. In many respects, it resembles a dedicated server process, but without a client connection.
Let's examine each of these background processes, starting with the ones that have a focused job, and then look into
the utility processes.
Focused Background Processes
The number, names, and types of focused background processes varies by release. Figure
5-4
depicts a
typical set
of
Oracle background processes that have a focused purpose:
Clustered
Instances
Shared Memory
Network
Disk I/O
LMDO
LCKn
LMSn
LMON
PMON
Block Buffers
Redo Log
SMON
SGA
RBCO
CKPT
DBWn
LGWR
ARCn
Database
Files
Remote
Database
Archive
Logs
Online Redo
Figure 5-4.
Focused background processes
■
For a complete diagram showing all Oracle 12
c
background processes and memory structures, see the file at
Tip
For example, in Oracle 12
c
Release 1, here's a database started using a minimum number of
init.ora
parameters.
SYS@ORA12CR1> create pfile='/tmp/pfile' from spfile;
File created.