That's right. The SCN corresponds to the "The checkpoint, i.e., a record indicating the point in the redo log such that all database changes prior to this point have been saved in the datafiles."
The part of my post that you included in your message was cut and pasted from the Oracle documentation.
The TR produced by NetApp is intended as an example of how to use Snapshots to backup an Oracle database.
It is certainly important that any DBA/SA familiarize themselves with the Oracle Backup and Recovery Guide, and fully understand what needs to be backed up in order to be able to recover from various failures as they relate to an Oracle Instance. It is also important that recovery scenarios be practiced.
The Snapshot technology simply gives the DBA a virtual online copy of the datafiles that are stored on the Filer. There are many parts of the Oracle database, and many variations on which parts any individual might store on a Filer for any given Oracle Instance. It is important that no parts that are required for recovery are forgotten during a backup.
-tom
-----Original Message----- From: Gustavo Chaves [mailto:gustavo@cpqd.com.br] Sent: Wednesday, August 16, 2000 8:02 AM To: toasters@mathworks.com Subject: Re: Snapshots and Oracle
"Yarmas" == Yarmas, Tom Tom.Yarmas@netapp.com writes:
Yarmas> The control file contains: The database name. The timestamp Yarmas> of database creation. The names of the database's datafiles Yarmas> and online and archived redo log files. The checkpoint, Yarmas> i.e., a record indicating the point in the redo log such Yarmas> that all database changes prior to this point have been Yarmas> saved in the datafiles. Information on backups (when using Yarmas> the Recovery Manager utility).
I'm no expert but W. Curtis Preston tells on page 459 of his book 'UNIX Backup & Recovery' (from O'Reilly) that Oracle's control files keep something called an SCN (System Change Number) for each database object. In particular, whenever a datafile is modified its SCN is incremented in it and in the control files. From this I gather that control files are changed after every database change, which means we *must* back them up whenever we backup the database.
Gustavo.