How is backup for Oracle Database with data 5 - 20 GB being performed?

As a MySQL user for quite a while managing mostly ~ megabytes of data, i have always wondered how are backups for Oracle database done. Currently, i am performing SQL dump (for ~ 30 mb of data) from开发者_JAVA技巧 SQL developer off a production server myself, and i am interested to know how this is done in practice.

You first choice is

Hot backup or Cold Backup. A Cold backup means shutting down the database, so isn't particularly useful for a 24x7 application. If this is a 9-5 job, then this might be viable. A cold backup is a snapshot at a point in time. If you don't mind the downtime, aren't fussed about activity after the backup, have small data volumes (and 20GB is small) then it is probably the simplest to do AND restore from.

Second choice is, do you need to "restore to as late a point as possible" (generally the case for a disk failure) or the facility to "restore to last Thursday" (eg for a month-end snaphot, or prior to some FUBAR). For those you need those archive logs. As Oracle runs, as well as writing to data files, it writes the changes to independent log files. When a log file is full, it can be archived (copied off elsewhere). Those files are needed to apply transactions that happen after the backup.

Third decision is, how long can you afford your database to be down for. Say you had a backup on Sunday and need to get to Thursday, that may take some time if you generate lots of transactions. But if you take backups each day, it makes it harder to get back to "last Thursday".

Mostly, the answer to Oracle backup questions is RMAN, which you can configure through the Enterprise Manager - once you've decided what your requirements are.

The trick of course, is not how to backup, but how to restore from that backup. Again, the answer is RMAN. But if you don't practice your restores you don't know how to recover, which puts you in a dangerous position if/when you do need to recover.