rajendra_thanekar

 Profile Answers by rajendra_thanekar 

• Jun 25th, 2008

 

hi,

In Oracle  we can take the backup of our database in two mode cold backup or hot backup.

When we want to take the hot backup of database when user is accessing the data, we can put the tablespace in backup mode.

fbchua

 Profile Answers by fbchua 

• Oct 17th, 2008

 

We need to put the tablespaces in backup mode during hot backup so that writing to datafiles related to this tablespace would stop and be written in the archive logs instead during the period of the backup.

If you will not put the tablespaces in backup mode and copy directly while the database is up, your backup would be not restorable.

dbashashi

 Profile Answers by dbashashi 

• Dec 2nd, 2010

 

We need to backup so that it can be used in case if any failure. We restore it from these backup. Now for the backup to be used for restore it has to be valid backup. Some thing like SCN, Timestamp has to be in consistant state. So that it can be applied against the same point in time while restoring.
Now you would have know as to why we take the tablespace in backup mode...just to get the consistant image of data while taking backup.
Though the work (Write) on the same tablespace is carried out but the header of the datafile associated with this backup is freezed. All of these changes are written to redo logs. In a otherwise situation when the database is not in backup mode..only the change vector is written to redo logs but in backup mode the entire changed block is writen to redo logs and that's reason why we see the redo logs getting filled very fast.

Sriniv@s..

• May 23rd, 2012

 

In case of hot backup,table space is put into backup mode.At the time ts related datafile header is frozen
because for taking backup with out any data loss.And after that any data is coming,that one going to redolog file for recovery.

Fabio

• Jun 9th, 2015

 

You do not use it anymore, you would have to use it in old Oracle versions when you did not have RMAN!