I need some clarification about hot backups. My doubt is
When issue the statement tablespace begin backup,DBWR write dirty blocks to datafile which contains the data files in that TS. After that sequence number frozen right, My data file size is very big. If concurrent users applying DMLs which related to that data file Where it writes new value and old value ? Where it store the data ? is it in Buffer Cache, Log Buffer and Redo log files ?
I am little bit confusion regarding. Please any one clarify.
During hot backup the DML operations work normally, that is all changes are recored in the datafiles as well as the redo normally, extra redo is generated to capture the block image of the blocks that is modified during the DML operation.
On begin backup command the file headerís checkpoint SCN is advanced to the SCN captured when begin backup command is issued. This is important as the checkpoint SCN in the backup files must be the same as when the backup started.
On end backup command Logging of block images is stopped and the data file checkpoints are advanced to the database checkpoint.
Amar "There is a difference between knowing the path and walking the path."