An Oracle table can have an index for improving performance. Without an index, Oracle scans every record just to find a specific record. Once the tablespace and subsequent tables are created by the DBA, data can be loaded into them for processing by the application. The redo log, also referred to as the transaction log, is a datafile that contains all transactions and updates that occur to an application database. Normally, data is de-staged from memory into the redo log for performance reasons.
Oracle switches redo logs when one fills up.
Possibilities include problems related to the application itself or the disk hardware on which the datafiles reside. Last, there is the control file that contains information Oracle needs to start a database. Most installations have two or more control files for critical databases. The files should reside on RAID devices or separate disk hardware devices. Native Oracle Backup and Recovery Overview Oracle provides several utilities that facilitate the backup and recovery of Oracle objects.