This thread is nothing to do with the reason why we need to backup undo. I just want to backup the undo segments which are required for recovery but not the entire undo datafile. (I know 11g skips commited before image but I am at 10g.) Thanks. On Tue, Dec 15, 2009 at 11:07 AM, MacGregor, Ian A. <ian@xxxxxxxxxxxxxxxxx>wrote: > The undo tablespace is required for database recovery > > Sent from my iPhone > > On Dec 15, 2009, at 8:51 AM, "Guillermo Alan Bort" <cicciuxdba@xxxxxxxxx> > wrote: > > Short answer... don't take a backup of the undo tablespace... it's not > required for database recovery. > > > > Alan.- > > > On Tue, Dec 15, 2009 at 1:20 PM, Roger Xu <wellmetus@xxxxxxxxx> wrote: > >> Good morning, >> >> Background: Windows 2003 / Oracle 10g with auto undo (8K block size) >> >> We have only one datafile (20 GB) in the undo tablespace. >> When I ran RMAN backup of this datafile, it created a 20GB backupset file. >> >> >> I query dba_undo_extents and it shows less than 80 MB used. >> >> SQL> select sum(blocks) from dba_undo_extents; >> SUM(BLOCKS) >> ----------- >> 9824 >> >> Any explanation? How do I keep the backup of undo small? >> >> Thanks, >> Roger Xu >> >> >> > >