Database Reference
In-Depth Information
Incremental level 1 backup:
Backs up only blocks that have been modified since the
previous backup. Level 1 incremental backups can be either differential or cumulative.
A differential level 1 backup is the default and backs up all blocks that have been modified
since the last level 0 or level 1 backup. A cumulative level 1 backup backs up all blocks that
have changed since the last level 0 backup.
Incrementally updated backup:
First creates an image copy of the data files, after which
subsequent backups are incremental backups that are merged with the image copy. This
is an efficient way to use image copies for backups. Media recoveries using incrementally
updated backups are fast because the image copy of the data file is used during the restore.
Block change tracking:
Database feature that keeps track of blocks that have changed in
the database. A record of the changed blocks is kept in a binary file. RMAN can use the
contents of the binary file to improve the performance of incremental backups: instead of
having to scan all modified blocks in a data file, RMAN can determine which blocks have
changed from the binary block change tracking.
Now that you understand the RMAN architectural components and the types of backups you can make, you're
ready to start up RMAN and configure it for your environment.
Starting RMAN
Before you start RMAN and connect to your database, you need to ensure that you have the proper OS variables set
and that you have access to an account with
sys*
privileges. Once those are in place, you can start RMAN and connect
to your target database via the
rman
command-line utility. These are the same conditions that need to be in place
before connecting to your database as a privileged user are described earlier in Chapter 1. You may want to review
Chapter 1 now if you're not familiar with these conditions.
You can connect to RMAN either through the operating system command-line interface or through Enterprise
Manager (EM). Using EM for backup and recovery is out of scope for this topic. This topic focuses on the command-
line interface for its examples.
■
even if you use the screen based enterprise Manager tool, it's useful to understand the rMan commands
used for backup and recovery operations. this knowledge the foundation for using rMan regardless of the interface.
this awareness is particularly useful when debugging and troubleshooting problems.
Tip
The following example assumes you have logged on to a Linux/Unix server using the
oracle
operating system
account assigned to a privileged group, such as
dba
and have established the required OS variables. You can then
invoke RMAN and connect to the target database as follows:
$ rman target /
Here is a snippet of the output:
connected to target database: O12C (DBID=3458744089)
If you're using a password file, then you need to specify the username and password that have been granted
proper system privileges:
$ rman target <user>/<password>
