Database Reference
In-Depth Information
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In oracle 12c, you can perform user-managed hot backups and cold backups on pluggable databases; the
user-managed backup and recovery technology works fine. however, I would strongly recommend that you use rMan
to manage backup and recovery in a pluggable environment. When connected to either the root container or a pluggable
container, rMan automatically determines which data files need to be backed up, their locations, and how to restore
and recover. this task quickly becomes unwieldy for user-managed backups, in which the dBa has to manage this
information for the root container and, potentially, numerous pluggable databases.
Tip
Implementing a Cold-Backup Strategy for a Noarchivelog
Mode Database
You perform a user-managed cold backup by copying files after the database has been shut down. This type of backup
is also known as an offline backup. Your database can be in either noarchivelog mode or archivelog mode when you
make a cold backup.
DBAs tend to think of a cold backup as being synonymous with a backup of a database in noarchivelog mode.
That isn't correct. You can make a cold backup of a database in archivelog mode, and that's a backup strategy
that many shops employ. The differences between a cold backup with the database in noarchivelog mode and in
archivelog mode are detailed in the following sections.
Making a Cold Backup of a Noarchivelog Mode Database
One main reason for making a cold backup of a database in noarchivelog mode is to give you a way to restore a
database back to a point in time in the past. You should use this type of backup only if you don't need to recover
transactions that occurred after the backup. This type of backup and recovery strategy is acceptable only if your
business requirements allow for the loss of data and downtime. Rarely would you ever implement this type of backup
and recovery solution for a production business database.
Having said that, there are some good reasons to implement this type of backup. One common use is to make
a cold backup of a development/test/training database and periodically reset the database back to the baseline.
This gives you a way to restart a performance test or a training session with the same point-in-time snapshot of the
database.
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Consider using the Flashback database feature to set your database back to a point in time in the past
(see Chapter 6 for more details).
Tip
The example in this section shows you how to make a backup of every critical file in your database: all control
files, data files, temporary data files, and online redo log files. With this type of backup, you can easily restore your
database back to the point in time when the backup was made. The main advantages of this approach are that
it's conceptually simple and easy to implement. Here are the steps required for a cold backup of a database in
noarchivelog mode:
1.
Determine where to copy the backup files and how much space is required.
2.
Identify the locations and names of the database files to copy.
Shut down the database with the
IMMEDIATE
,
TRANSACTIONAL
, or
NORMAL
clause.
3.
