There are three types of process in Oracle Database 11g XE:
Background processes: These are the processes that start and stop the database. They are also responsible for writing blocks to the disk, maintaining the online redo log, and performing other background jobs.
Server processes: These processes perform work based on the client's request. Tasks performed by these processes include loading data from the disk to SGA, modifying blocks in memory, and so on.
Slave processes: These processes perform jobs on behalf of background or server processes.
We will look at the important background processes:
Database Block Writer (DBWn): This is responsible for writing dirty (modified) blocks to the disk, thus making buffer space available. More than one DBWn process can be configured to enhance the writing of dirty blocks to the disk.
Log Writer (LGWR): This is responsible for flushing the contents of the redo log buffer to online redo logfiles. It flushes...