Quote:
Originally posted by ggnanaraj
When a tablespace(tbs) is in 'backup mode' the headers of the datafiles in that tbs are freezed and no entry is made to the datafile but to the redo logs instead. So, what ever changes are made to this datafile the entries are placed in the redo log, this can generate a lot of redo logs and overhead to LGWR.
Well, I think a minor correction is required. While tablespace is in backup mode, its files headers realy are "freezed", but the changed datablocks are still written to the datafiles all the time.