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.g." If the channel is of type disk, the server process will attempt to readbackups from, or write backups to disk." If the channel is of type SBT_TAPE , the server process will attempt toread backups from or write backups to a Media Manager.Channels are always able to read and write datafiles to and from disk, nomatter what their type.checkpointWhen a checkpoint occurs, all modified database buffers in the SGA arewritten to the datafiles by DBWR.Once the checkpoint completes, thedatafiles and control files are modified to reflect the fact that it hassuccessfully completed.Glossary-3checksumAn Oracle internal computed number stored in an Oracle block, whichallows Oracle servers to validate the consistency of the block.clean shutdown (see shutdown clean)clone databaseA subset of a database which is restored to a new location, and started upwith a new instance name.The intended use of a clone database is usuallyto perform tablespace point-in-time recovery.A clone database consists ofthe recovery set and auxiliary set.The clone database has varioussubstantive differences from a regular database copy.closed backupA backup of one or more database files taken while the database is closed.Typically, closed backups are also whole database backups.If the databasewas closed cleanly, it means the all the files in the backup are consistent (seedatabase backups - consistent, for more information).If the database wasclosed using a shutdown abort or the instance terminated abnormally, thebackup must be recovered before it is consistent.closed databasesee database closedcold backupsee closed backupcomplete recoverysee recovery completecontrol fileA file associated with a database that maintains the physical structure andtimestamps of all files in that database.The control file is updatedcontinuously during database use, and must be available for writingwhenever the database is mounted or open.control file backupA backup control file is a backup of the control file.Backup control files aretypically restored when all copies of the current control file are damaged,and are sometimes restored before performing certain kinds of point-in-timerecovery.Glossary -4 Oracle8 Backup and Recovery Guidecontrol file currentThe current control file is the control file on disk - it is the most recentlymodified control file for that incarnation of the database.For a control file tobe considered current during recovery, it must not have been restored frombackup.consistent database backupsSee database backups consistentcopy generic termTo copy:To make a replica of an original.It is possible to take copies of Oracle datafiles, control files, and archivedredo logs in two ways: 1.using Operating System utilities (on Unix onecould use cp, or dd).2.using the Recovery Manager copy command.copy Recovery Manager commandA Recovery Manager keyword, which when used, will make a replica of adatabase's datafiles, control file or archived redo log.This replica is made byOracle server process, allocated to a Recovery Manager channel, whichreads the Oracle file, and writes a replica out to disk.An open database'sdatafiles can be copied using Recovery Manager without putting thedatabases' tablespaces into hot backup mode.corrupt blockAn Oracle block which is not in a recognized Oracle format, or whoseinternal contents are not consistent.Oracle identifies corrupt blocks as one oftwo types:" logically corrupt: The block was corrupted by the application of redo" media corrupt: The block format is not correct.To be identified as mediacorrupt, the block may:- have an impossible format- have a wrong data block Address- impossible block typeThe only way a media corrupt block can be repaired, is:" by replacing the block, and recovering.For example, the block isreplaced when the datafile is restored, or when the block is replaced bya newer version when applying an incremental backup.Glossary-5" by renewing the block [ Pobierz całość w formacie PDF ]

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