datafile erased

[Hunan_1]

Hi all, I???m starting to work with ORACLE , so I wanna clear many doubts
What should be done to recover a datafile delete.
Supposing that I have a full backup of my OS including all the datafiles.
It???s the same than recover a file?
I would be really pleased if someone could explain me a little about it.

[Thomas Schler_1]

Hunan,

along with the Oracle documentation you should have the "Backup And Recovery Guide". It is very detailed and helps you in all standard situations.

How to recover datafiles depends on what kind of datafiles (physical database structure, files containing tables, redo log files, control files, and so on) you have to recover. Additionally, it depends on your choice of recovery procedure (with or without ARCHIVELOG mode, using export or import facilities).

If you have a full backup of your system (including Oracle), this backup is ready to use, if all your Oracle instances were shut down, while creating the backup. If you would do a recovery of your Oracle system, you would have to start Oracle with the RESETLOGS option after recovering.

If the full backup is created when Oracle is up and running, tha backup cannot be used to recover Oracle later. The Oracle system would be very likely unusable.

[Brian Crabtree · Accepted solution]

If you have deleted a datafile, it depends entirely on if your database is in archivelog mode, and when your last backup was run.

An offline backup can be used for this purpose, as well as an online backup. You would need to restore whatever datafile was deleted, and then run the following:

recover database datafile '';

This will force the datafile into a recovery state, and begin looking for logs required to bring the datafile up to the current SCN. Once the datafile is up to the current SCN, the datafile will be available (if the database is open), or the instance can be brought up without needing to perform a RESETLOGS. Remember that you might need to specify an online log to complete the cycle. Online logs that have not been archived are valid for this purpose, but the full path to the log will need to be input.

If you do not have the logs required to bring the datafile up to the correct SCN, then you will need to perform an incomplete database recovery (all of the datafiles), and open with a RESETLOGS, or a recovery from an offline backup. There isn't a way to bring a datafile that has not been recovered up to the current SCN online.

Hope this answers your questions,

Brian

[Hunan_1]

Thanks a lot friends, Your help went direct to the point.
Does anyone know a web address with good information related to oracle backups with some examples and situations?

[Yogeeraj_1]

Hi,

Try metalink.oracle.com (you will need an account there - if you are a Oracle customer and you have your CSI number, there should not be any problems!) - do a search on "Backup and Recovery" you have tons of information.

otherwise, you can also visit the following pages:
http://otn.oracle.com/docs/products/oracle8i/doc_library/817_doc/server.817/a76993/backupst.htm

http://otn.oracle.com/docs/products/oracle9i/doc_library/901_doc/server.901/a90134/intro.htm

Hope this helps!
Best Regards
Yogeeraj

[Yogeeraj_1]

hi again,

Another interesting document that i can across today.

It's about:
Media Recovery Scenarios

and describes how to recover from common media failures, and includes the following:

- Understanding the Types of Media Failures
- Recovering After the Loss of Datafiles
- Recovering Through an ADD DATAFILE Operation
- Recovering Transported Tablespaces
- Recovering After the Loss of Online Redo Log Files
- Recovering After the Loss of Archived Redo Log Files
- Recovering After the Loss of Control Files
- Recovering from User Errors
- Performing Media Recovery in a Distributed Environment

URL:
http://technet.oracle.com/doc/oracle8i_816/server.816/a76993/recoscen.htm

Hope this helps!
Best Regards
Yogeeraj

[Yogeeraj_1]

hi again,

Today, i came across the following interesting documents:

A. Oracle9i Data Guard-Technical White Paper
Oracle9i introduces many new features that address the data protection challenge. The feature this paper will focus on is Oracle9i Data Guard. Oracle9i Data Guard can be configured to protect data from all causes of data loss whether from human error, operating system induced corruptions, natural disasters and terrorism.
http://technet.oracle.com/deploy/availability/pdf/Oracle9i_DG_TWP072001.pdf

B. Fast-Start: Quick Fault Recovery in Oracle
This paper highlights Fast-Start??? Fault Recovery, an important availability feature in Oracle, designed to expedite recovery from unplanned outages. Fast-Start allows the administrator to configure a running system to impose predictable bounds on the time required for crash recovery.
http://technet.oracle.com/deploy/availability/pdf/fast-start.pdf

Hope this helps!
Best Regards
Yogeeraj