由 macro 发布于: 2001-03-01 11:59

Online Redo Log Groups

1.A set of identical copies of online redo log files is called an online redo log group.

2.The LGWR background process concurrently writes the same information to all online redo log files in a group.

3.The oracle server needs a minimum of two online redo log file groups for the normal operation of a database.

Online Redo Log Members

1.Each online redo log file in a group is called a member.

2.Each member in a group has identical log sequence numbers and the same size.(The log sequence number is assigned each time the oracle server starts writing to a log group to indentify each redo log file uniquely. The current log sequence number is stored in the control file and in the header of all data files.)

由 macro 发布于: 2001-03-01 12:34

Creating initial redo log files

The initial set of redo log groups and members are created during the database creation.

The following parameters limit the numbers of online redo log files:

1.MAXLOGFILES specifies the absolute maximum of online redo log groups.

2.MAXLOGMEMBERS determines the maximum number of members per group.

3.LOG_FILES sets the current maximum number of the log groups that can be opened at run time for the database ,and cannot exceed MAXLOGFILES.(This parameter has been make obsolete in release 8.1 to simplify database administration)