Does Oracle write to data files in begin/hot backup mode?
Oracle will stop updating file headers, but will continue to write data to the database files even if a tablespace is in backup mode. In backup mode, Oracle will write out complete changed blocks to the redo log files. Normally only deltas (changes) are logged to the redo logs. This is done to enable reconstruction of a block if only half of it was backed up (split blocks). Because of this, one should notice increased log activity and archiving during on-line backup. and on URL: http://orafaq.com/wiki/Hot_Backup’s What Happens during Hot Backup’s??? When alter tablespace begin backup is issued, the datafiles which belongs to the tablespaces are flagged as hot-backup-in-progress. The command would checkpoint all data files that are in the hot backup mode. I.e DBWR is asked to write dirty database block buffers to files, and LGWR or CKPT will update the file headers with the current SCN number. An interesting point to pay attention to is the concept of “split blocks”. For example let us
