Database Reference
In-Depth Information
Making a Hot Backup
Here are the steps required for a hot backup:
1.
Ensure that the database is in archivelog mode.
2.
Determine where to copy the backup files.
3.
Identify which files need to be backed up.
4.
Note the maximum sequence number of the online redo logs.
5.
Alter the database/tablespace into backup mode.
6.
Copy the data files with an OS utility to the location determined in step 2.
7.
Alter the database/tablespace out of backup mode.
8.
Archive the current online redo log, and note the maximum sequence number of the
online redo logs.
9.
Back up the control file.
10.
Back up any archive redo logs generated during the backup.
These steps are covered in detail in the following sections.
Step 1. Ensure That the Database Is in Archivelog Mode
Run the following command to check the archivelog mode status of your database:
SQL> archive log list;
The output shows that this database is in archivelog mode:
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /u01/oraarch/O12C
If you're not sure how to enable archiving, see Chapter 2 for details.
Step 2. Determine Where to Copy the Backup Files
Now, determine the backup location. For this example the backup location is the directory /u01/hbackup/O12C .
To get a rough idea of how much space you need, you can run this query:
SQL> select sum(bytes) from dba_data_files;
Ideally, the backup location should be on a set of disks separate from your live data files. But, in practice, many
times you're given a slice of space on a SAN and have no idea about the underlying disk layout. In these situations, you
rely on redundancy's being built into the SAN hardware (RAID disks, multiple controllers, and so on) to ensure high
availability and recoverability.
 
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