RE: while taking hotbackup (begin end backup) what wi...
When we r taking hot backup(begin backup - end backup) ,the datafile heder associated with the datafiles in the corresponding tablespace is frozen.So Oracle will stop updating the datafile header, but will continue to write data into datafiles.In backup oracle will generate more redos , this is beacause oracle will write out complete changed blocks to the redo log files.
RE: while taking hotbackup (begin end backup) what wi...
The two things will happen when the tablespace in backup mode
1.) The datafile header associated with the tablespace in the backup up mode will be in frozen state.So it stops updating the datafile header, but it continually writes into the datafile.
2.) More redos are generated.This is because oracle will write all the changed blocks into the redo log.Normally only the changes are logged into the redo logs.
RE: while taking hotbackup (begin end backup) what wi...
Hi
Everyone ..Answer given by all others are right and i am just adding a brief to it. actually what happens in backend when a tablespace is put up in backup mode is that the all datafile belonging the tablespace gets their checkpoint frozen. which means that next time the recovery should start after the checkpoint anything after the checkpoint is roll backward or roll forward to maintain consistency. At the same time database writter process writes to the datafile all the data blocks and the same data blocks are written to redo log files this is because the oracle block size and OS block sizes differs which results in fractured block to be copied by the OS utilities and for that reason when the file backuped up by hot backup required recovery and any fractured blocks are found out they are replaced by the actual block from archived log which are copy of redo logs.RMAN doesn't requires the tablespace to be put in the backup mode because oracle understands the block size and skips the block if a process is making change to it at the time of the backup.when you put the tablespace end backup the checkpoint is released and marked wih current checkpoint No and in this way oracle maintains consistency in the database.
6. What is a logical backup? Logical backup involves reading a set of database records and writing them into a file. Export utility is used for taking backup and I
7. What is Partial Backup ? A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
RE: While taking hot backup (begin end backup) what w...
When the database is taken in backup mode the checkpoint takes place and the datafile header gets frozen As the checkpoint takes place the database writer writes all the blocks from database buffer cache to datafiles.The same blocks are also written from the redo log buffer in the redo log files. So the archive log generation becomes high OS blocks differ from oracle blocks so there can be fractured block that needs recovery. This is the reason why all the blocks are written in the redolog files when the database is in backup mode
