Availability and Recovery - New and Changed Oracle Database 10g Database Backup Commands
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Oracle Database 10g offers a new way to start database backups, with the alter database begin backup command. Also, Oracle Database 10g offers new functionality with the alter database end backup command. Let’s look at each of these features in a bit more detail next.
The New alter database begin backup Command
Are you tired of issuing alter tablespace begin backup over and over? Now, putting the entire set of database tablespaces in hot backup mode is as simple as issuing the alter database begin backup command, as shown in this example:
SQL> alter database begin backup;
Jonathan Says… Of course, the traditional advice is to never put your entire database into hot backup mode at once—so you have to ask yourself why Oracle has now made it very easy to do exactly that. Moreover, why do you need this command at all, when RMAN doesn’t require the database to be in hot backup mode at all? As ever, Oracle is giving you lots of options, and you have to decide which one is relevant to your system. If your backup strategy ignores Oracle features and uses a simple “split mirror” approach, you are the one customer who should really be pleased with this new command. |
If there are already tablespaces in hot backup mode, then the Oracle database will raise an error (ORA-01146). Also, the following conditions cause an error to be returned by the
alter database begin backup command:
- One or more datafiles are offline or missing
- An RMAN backup is ongoing
Once you have issued the alter database begin backup command successfully, you can proceed to back up your Oracle database. As is the case when you put individual tablespaces in hot backup mode, you will be unable to perform a normal or immediate shutdown on the database after issuing this command. However, you can issue shutdown abort to terminate the instance if that is required (although one would hope this would never be required).
If the instance crashes or you use the shutdown abort command, you need to take the database out of hot backup mode by using the alter database end backup command … and that is a nice segue to the next topic!
Changes to the alter database end backup Command
The alter database end backup command has been around since Oracle9i Database, and its functionality is enhanced in Oracle Database 10g. Previously, the alter database end backup command could be used only when the database was mounted. In Oracle Database 10g, you can use this command to end backups with the database mounted or the database open—your choice! Here is an example of the use of this command:
SQL> alter database end backup;
NOTE -- A warning will be issued if any datafiles/tablespaces are not in hot backup mode, but the command will complete successfully.
 This chapter is from Oracle Database 10g New Features, by Robert Freeman (McGraw-Hill/Osborne, 2004, ISBN: 0072229470). Check it out at your favorite bookstore today. Buy this book now.
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