Consistent and Inconsistent Backups - wykład

Consistent and Inconsistent Backups
A backup is either consistent or inconsistent. To make a consistent backup, your
database must have been shut down cleanly and remain closed for the duration of the
backup. All committed changes are written to the data files during the shut down
process, so the data files are in a transaction-consistent state. When you restore your
data files from a consistent backup, you can open the database immediately.
If the database is in ARCHIVELOG mode, then you can make inconsistent backups that
are recoverable using archived redo log files. Open database backups are inconsistent
because the online redo log files contain changes not yet applied to the data files. The
online redo log files must be archived and then backed up with the data files to ensure
recoverability.
Despite the name, an inconsistent backup is as robust a form of backup as a consistent
backup. The advantage of making inconsistent backups is that you can back up your
database while the database is open for updates.
... zobacz całą notatkę