Objectives: explain the purpose of online redo log file; outline the structures of online redo log file; control log switches and checkpoints; multiplexing and maintain online redo logs; manage with OMF; Obtain online redo log file information;
■Using online redologfile; Record all changes made to data; Provide a recovery mechanism; Can be organized into groups; at least two groups required; ■Structures of redo log file; concepts: online redo log file group; LGWR; mininum of two online redo log file; member; log sequence numbers(LSN); ■Multiplexed Redo log file
■How redo files work log switch:the act of switching from one log file group to others; checkpoint :the writing of dirty(modified)blocks from the buffer cache to disc
