10g Release 1 (10.1) Part Number B10735-01 |
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10g Release 1 (10.1) Part Number B10735-01 |
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A copy of one of the filled members of an online redo log group made whe
n the database is in ARCHIVELOG mode. After the LGWR process fills each online redo log with redo records, the archiver
process copies the log to one or more offline redo log archiving destinations. This copy is the archived redo log. Note that RMAN doe
s not distinguish between an original archived redo log and an image copy of an archived redo log; both are considered image copies.<
/p>
The mode of the database in whic
h Oracle copies filled online redo logs to disk. Specify the mode at database creation or with the ALTER DATABASE<
/code> ARCHIVELOG statement. Oracle automatically performs the archiving unless you execute ALTER DAT
ABASE ARCHIVELOG MANUAL.
See Also: archived redo log, NOARCHIVELOG mode
The operation in which the archiver background process copies filled online redo logs to offline destinations. An offline copy of an
online redo logs is called an archived redo log. You must run the database in ARCHIVELOG mode to archive redo logs.
The persistent preconfiguration of RMAN channels. You
can use the CONFIGURE command to specify disk and tape channels. Then, you can issue commands such as BACKUP and RESTORE at the RMAN command prompt without manually allocating channels. RMAN uses whatever preallocated channels
that it needs in order to execute the commands.
A mode of the database in which undo data is stored in a dedicated
(1) A database created from target database backups with the RMAN DUPLICATE command.
(2) A temporary database that is restored to a new location and then started up with a new instance na me during tablespace point-in-time recovery (TSPITR). A TSPITR auxiliary database contains the recovery set and auxiliary set.
See Also: recover y set, auxiliary set
In TSPITR, the set of files that is not in the recovery set but which must be restored in the auxiliary database for the TSPITR set to be successful.
See Also: auxiliary database, recovery set
(1) A backup of data, that is, a database, tablespace, table, datafile, control file, or archived redo log. You can m ake a backup by:
(2) An RMAN command that creates a backu p set, proxy copy, or disk-based image copy.
See Also: copy, backup set , multiplexing, RMAN
The set of concepts, procedures, and strategies invo lved in protecting the database against data loss due to media failure or users errors. In a wider sense, backup and recovery also in volves maintenance of backups and their associated metadata.
A backup of the control file. You can back up the control file with the RMAN backup com
mand or with the SQL statement ALTER DATABASE BACKUP CONTROLFILE TO
'filename'
The database mode (also called hot backup mode) initiated when you issue
the ALTER TABLESPACE ... BEGIN BACKUP or ALTER D
ATABASE BEGIN BACKUP command before taking an online backup. You take a tablespace out of backup mod
e when you issue the ALTER TABLESPACE ... END BACKUP or ALTER<
/code> DATABASE END BACKUP command.
You must use this command when you make a user-managed backup of datafiles in an online tablespace. RMAN does not require you to put the database in b ackup mode. Updates to tablespaces in backup mode create more than the usual amount of redo because each change causes Oracle to writ e the entire block rather than just the changed data to the redo log.
S
ee Also: corrupt block,
A backup piece is a physical file in an RMAN-specific format that belongs to only one backup set. A backup set usually contain
s only one backup piece. The only time RMAN creates more than one backup piece in a backup set is when you limit the backup piece siz
e using the MAXPIECESIZE option of the ALLOCATE or CONFIGURE command.
See Also: backup, backup set, RMAN
See retention policy
A backup of one or more datafiles, control files, archived logs, or backup se
ts produced by the RMAN BACKUP command. A backup set is a logical grouping of one or more binary files called backup pieces. Backup sets are in a proprietary format and can only be restored by RMAN.
See Also: backup piece, unused block compression,
An RMAN option that improves incremental back up performance. RMAN maintains a block change tracking file in the flash recovery area. This file logs a record of changed blocks, wh ich RMAN can then read during an incremental backup so that it does not have to perform a full scan of the datafiles.
The recovery of specified blocks within a
datafile with the Recovery Manager BLOCKRECOVER command. Block media recovery leaves the affected datafiles online and r
estores and recovers only the damaged or corrupted blocks.
A connection between RMAN and the target database. Each allocated channel starts a new Oracle server session; the
session then performs backup, restore, and recovery operations. The type of channel (DISK or sbt) determine
s whether the Oracle server process will attempt to read or write and whether it will work through a third-party media manager.
See Also: media manager, target database
A data structure that defines an SCN in the redo thread of a databas e. Checkpoints are recorded in the control file and each datafile header, and are a crucial element of recovery.
Control file records containing non-critical
information used by RMAN for backups and recovery operations. These records are arranged in a logical ring. When all available record
slots are full, Oracle either expands the control file to make room for a new records or overwrites the oldest record. The CON
TROL_FILE_RECORD_KEEP_TIME initialization parameter controls how many days records must be kept before it can be overwritten.
The default for CONTROL_FILE_RECORD_KEEP_TIME is 7 days.
S ee Also: noncircular reuse records
A backup of one or more database files taken while the data base is closed. Typically, closed backups are whole database backups. If you closed the database cleanly, then all the files in the b ackup are consistent. Otherwise, the backups are inconsistent.
See Also : consistent shutdown, consistent backup
See closed backup
Recovery of one or more datafiles that applies a ll online and archived redo generated after the restored backup. Typically, you perform complete recovery when media failure damages one or more datafiles or control files. You fully recover the damaged files using all redo generated since the restored backup was ta ken.
See Also: incomplete recovery, media recovery
How RMAN conserves space by writing onl y used data blocks into RMAN backup sets. A newly created datafile contains many never-used blocks. When RMAN creates backup sets, it only includes blocks that have been used.
RESETLOGS option without performing media recovery. In other words, you do not need to apply redo to this backup for it to be
consistent. You can only take consistent backups after you have made a consistent
shutdown of the database. The database must not be opened until the backup has completed.
See Also: fuzzy file, inconsistent backup
IMMEDIATE, TRANSACTIONAL
, or NORMAL options of the SHUTDOWN statement. A database shut down cleanly does not require recovery; it i
s already in a consistent state.The automatic backup of the current control file that RMAN makes in the situations:
BACKUP command run at the RMAN promptBACKUP command within a RUN block that is not followed by another BACKUP commandThe control file autobackup has a default filename that allows RMAN to resto re it even if the control file and recovery catalog are lost. You can override the default filename if desired.
To back up a bit-for-bit image of an Oracle file (Oracle datafil es, control files, and archived redo logs) onto disk. You can copy in two ways:
cp or dd)BACKUP AS COPY commandSee Also: backup
An Oracle block that is not in a re cognized Oracle format, or whose contents are not internally consistent. Typically, corruptions are caused by faulty hardware or oper ating system problems. Oracle identifies corrupt blocks as either logically corrupt (an Oracle internal error) or media corrupt (the block format is not correct).
You can only repair a media corrupt block by recovering the bl ock and or dropping the database object that contains the corrupt block so that its blocks are reused for another object. If media co rruption is due to faulty hardware, neither solution will work until the hardware fault is corrected.
See Also: block media recovery
The automatic application of on line redo records to a database after either a single-instance database crashes or all instances of an Oracle Real Applications Clust er configuration crash. Crash recovery only requires redo from the online logs: archived redo logs are not required.
See Also: recover< /a>
A check to determine whether file
s on disk or in the media management catalog correspond to the data in the repository and the control file. Because the media manager can mark tapes as expired or unusable, and because files can be dele
ted from disk or otherwise become corrupted, the RMAN repository can contain outdated information about backups. Run the CROSSC
HECK command to perform a crosscheck. To determine whether you can restore a file, run VALIDATE BACKUPSET or RESTORE ... VALIDATE.
S ee Also: validation
An incr emental backup that backs up all the blocks changed since the most recent backup at level 0. When recovering with cumula tive incremental backups, only the most recent cumulative incremental backup needs to be applied.
See Also: differential incremental backup, incremental backup
The online re do log file in which the LGWR background process is currently logging redo records. Those files to which LGWR is not wri ting are called inactive.
See Also: redo log, redo log groups
< a name="432522">The thread checkpoint that has th e lowest SCN. The database checkpoint guarantees that all changes in all enabled threads prior to the database checkpoint have been w ritten to disk.
See Also:
See DBID
The recovery of a database to a specified noncurrent time, SCN , or log sequence number.
See Also: incomplete recovery, tablespace point-in-tim e recovery (TSPITR)
The application of redo records to a restored datafile in order to roll it forward to a more current time. Unless you are do ing block media recovery, the datafile must be offline while being re covery.
An internal, uniquely generated num ber that differentiates databases. Oracle creates this number automatically when you create the database.
A type of
See Also: cumul ative incremental backup, incremental backup
A hardware component that is responsible fo r controlling one or more disk drives.
A user-specified limit to the size of the flash recovery area. When the disk quota is reached, Oracle automatically deletes files that are no longer needed.
A database created from target database backups using the RMAN duplicate command.
See Also: auxiliary database
The extraction of logical data (that is, not physical files) from a database into a binary file using the Oracle export utility. You can then use the Oracle import utility to import the data into a database.
See Also: logical backups
An optional disk location that you can use to store recove ry-related files such as control file and online redo log copies, archived logs, flashback logs, and RMAN backups. Oracle and RMAN ma nage the files in the flash recovery area automatically. You can specify the disk quota, which is the maximum size of the flash recovery area.
Oracle-generated logs, similar to archived redo logs, used by the FLASHBACK com
mand. Oracle can only write flashback logs to the flash recovery area. They cannot be backed up to disk.
A non-incremental RMAN backup. Note that "full" does not refer t o how much of the database is backed up, but to the fact that the backup is not incremental. Consequently, you can make a full backup of one datafile.
An RMAN
operation that updates the recovery catalog with all changed metadat
a in the database's control file. You can initiate a full catalog resynchronizatio
n by issuing the RMAN command RESYNC CATALOG. RMAN resynchronizes as needed when executing cer
tain commands.
A datafile that contai ns at least one block with an SCN more recent than the checkpoint SCN in its header. For example, this situation occurs when Oracle u pdates a datafile that is in backup mode. A fuzzy file that is restor ed always requires recovery.
See online backup
See backup mode
A bit-for-bit copy of a single datafile, archived redo log file, or c ontrol file that is:
BACKUP AS cp, or by the Oracle archiver processA redo log file that is not required f or crash or instance recovery because the changes contained in its redo records have already been applied to the database. The current online redo log is never inactive. If you operate the database in < code>ARCHIVELOG mode, the archiver process archives inactive redo log files.
See Also: online redo log, redo log, redo log groups
A separate version of a physical da
tabase. The incarnation of the database changes when you open it with the RESETLOGS option, but you can recover backups
from a prior incarnation so long as the necessary redo is available.
The recovery of a database in which you do not apply all of the changes generated since you created the restored backup. Is it the same as database point-in-time recovery (DB PITR).
See Also: complete recovery, media recovery, recover
A backup in which some of the files in the backup contain changes that were made after the files were checkpointed. This type of backup needs recovery before it can be made consistent. Inconsistent backups are usually create d by taking online database backups. You can also make an inconsistent backup by backing up datafiles while a database is closed, eit her:
ABORTInconsistent backups are only useful if the datab
ase is in ARCHIVELOG mode.
See Also: consistent backup, online back up, system change number (SCN), whole database backup
An RMAN backup in which only modified blocks are backed up. Incremental backups are classified by level. An incremental level 0 backup performs the same function as a full backup in that they bot
h back up all blocks that have ever been used. The difference is that a full backup will not affect blocks backed up by subsequent in
cremental backups, whereas an incremental backup will affect blocks backed up by subsequent incremental backups.
Incremental backups at level 1 back up only blocks that have changed since previous incremental backups. Blocks that have not changed are not backed up. An incremental backup can be either a dif ferential incremental backup or a cumulative incremental backup. A cumulative incremental backup backs up all blocks changed since the last level 1 incremental backup. A differential increm ental backup backs up all blocks changed since the last level 0 or level 1 incremental backup.
The termination of an Oracle instance due to a hardware failure, appl
ication error, or SHUTDOWN ABORT statement. Strictly speaking, an instance failure occurs whenever the data
base is not shut down consistently. Crash or instance recovery is always required after an instance failure.
In a RAC configuration, the application of redo data t o an open database by an instance when this instance discovers that another instance has crashed.
A utility that enables log files to be read, analyz ed, and interpreted by means of SQL statements
See Also: archived redo log
A number that uniquely identifies a set of redo records in a redo log file. When Ora cle fills one online redo log file and switches to a different one, Oracle automatically assigns the new file a log sequence number.< /p>
See Also: l og switch, redo log
The point at which LGWR stops writing to the active redo log file and swi tches to the next available redo log file. LGWR switches when either the active log file is filled with redo records or you force a s witch manually.
See Also:
Backups in which an Oracle export utility extracts database data and then saves it to a binary file at the operating system leve l. You can then import the data back into a database with the corresponding Oracle import utility.
A backup that you want to exclude from a backup retention policy, but want to record in the recovery catalog. Typically, long-term backups are snapshots of the database that you may want to use in t he future for report generation.
A physical problem that arises when Oracle fails in its attempt to write or read a file that is required to operate the database. Disk failure can affect a variety of files, in cluding the datafiles, redo log files, and control files. Because the database instance cannot continue to function properly, it cann ot write to the datafiles.
See Also: media recovery
A utility provided by a third party vendor that is capable of actions such as loading, labelling and unloading se quential media such as tape drives. Media managers also allow you to configure media expiration and recycling, and may also have the ability to control an ATL (automated tape library).
The application of redo or incremental backups to a restored backup datafile or individual data block to bring it to a specified time. Datafile media recovery always begins at the lowest SCN recorded in the datafile headers.
< /a>When performing media recovery, you can recover a database, tablespace, datafile, or set of blocks within a datafi
le. In ARCHIVELOG mode, you have the choice of complete recovery or incomplete recovery. In NOARCHIVELOG mode, t
he only option is typically to restore from the most recent backup without applying redo.
See Also: block media recovery, recover
Maintaining identical copies of data on one or more disks. Typically, mirroring is performed on duplicate ha rd disks at the operating system level, so that if one of the disks becomes unavailable, the other disk can continue to service reque sts without interruptions. When mirroring files, Oracle writes once while the operating system writes to multiple disks; when multiplexing files, Oracle writes the same data to multiple files.
The automated maintenance of more than one identical cop y of the online redo log.
The automated maintenance of more than one identical copy of a database's control file.
The RMAN technique of reading database files simultaneously from the disks and then writing the blocks t o the same backup piece.
The Oracle archiver process is able to archive multiple copies of a redo log.
See Also: mirroring
The mode of the database in which Oracle does not require filled online redo logs to be archived before they can be ov
erwritten. Specify the mode at database creation or change it with the ALTER DATABASE NOARCHIVELOG command. Note that running in NOARCHIVELOG mode severely limits the possibilities for recovery of lost data.
See Also: archive d redo log, ARCHIVELOG mode
< h5 class="GTM">noncircular reuse recordsControl file records containing critical informati on needed by the Oracle database. These records do not change often and cannot be overwritten. Some examples of information in non-ci rcular reuse records include datafiles and online redo logs.
See Also:< /strong> circular reuse records
A backup of a tablespace or datafile made when the tablespace or dataf
ile is offline and the database open. Run the ALTER TABLESPACE OFFLINE statement to take a tab
lespace offline, and the ALTER DATABASE DATAFILE ... OFFLINE stateme
nt to take an individual datafile offline.
When a tablespace is taken offline normal, it is taken offline using the ALTER TABLESPACE .
.. OFFLINE NORMAL statement. The datafiles in the tablespace are checkpointed and do not require rec
overy before being brought online. If a tablespace is not taken offline normal, then its datafiles must be recovered before being bro
ught online.
A backup of one or mo
re datafiles taken while a database is open and the datafiles are online. When you make a user-managed backup while the database is o
pen, you must put the tablespaces in backup mode by issuing an
ALTER TABLESPACE BEGIN BACKUP command. (ALTER DATABASE
BEGIN BACKUP is an alternative when your database has many tablespaces, all of which need to be put in backup mod
e.) When you make an RMAN backup while the database is open, however, you should not put the tablespaces in backup mode.
The online redo log is a set of two or more files that record all changes made to Oracle datafiles and control files. Whenever a change is made to the database, Oracle generates a redo record in the redo buffer. The LGWR process flushes the contents of the redo buffer into the online redo log.
The current online redo log is the one bein
g written to by LGWR. When LGWR gets to the end of the file, it performs a log swi
tch and begins writing to a new log file. If you run the database in ARCHIVELOG mode, then the archiver pro
cess or processes copy the redo data into an archived redo log.
See Also: archiv ed redo log
T he Oracle online redo log consists of two or more online redo log groups. Each group contains one or more identical online redo log m embers. An online redo log member is a physical file on the operating system containing the redo records.
A physical online redo log file within an online redo log group. Each log group must have one or more members. Each member of a group is identical.
See user-managed back up and recovery
The return of the whole database to a prior consistent SCN by means of the RMAN FLASHBACK command or SQL*Plus
A database file managed by the Oracle Managed Files feature .
A feature of the Or acle database which manages the creation, naming and deletion of Oracle database files within dedicated areas of disk, to minimize th e need for DBAs to concern themselves with such specifics.
Backups that are unusable because they belong to incarnations of the database that are not direct ancesto rs of the current incarnation.
A form of recovery in which several processes simultaneously apply changes from redo log files. Instance and media recovery can be p
arallelized automatically with the RECOVERY_PARALLELISM initialization parameter or options to the SQL*Plus RECOVE
R command.
Allocating mul tiple channels for RMAN backup and recovery operations.
A type of resynchronization in whic h RMAN transfers data about archived logs, backup sets, and datafile copies from the target control file to the recovery catalog.
A file created by the ORAPWD command. A database must use password files if you wish to conn
ect using the SYSDBA or SYSOPER roles over a network. For a more comprehensive explanation, see the Oracle Database Administrator's Guide.
The datafiles, control files, and redo l
ogs in a database at a given time. Issue the RMAN REPORT SCHEMA command to obtain a list of tablespaces and
datafiles.
A backup in which the media manager takes over the transfer of data between the media storage device and disk during RMAN backup and restore operations.
To recover a database file or a database is typi cally to perform media recovery, crash recovery or instance recovery. Can also be used generically, as in "recover your data," to ref er to reconstructing or re-creating lost data by any means.
See Also: recover
When used to refer to a database file or a database, the application of redo data or increme
ntal backups to database files in order to reconstruct lost changes. The three types of recovery are instance recovery, crash recovery, an
d media recovery. Oracle performs the first two types of recovery aut
omatically using online redo records; only media recovery requires you to restore a backup and issue commands.
See Also: complete recovery, incomplete recovery
A set of Oracle tables and views used by RMAN to store information abou t Oracle databases. RMAN uses this data to manage the backup, restore, and recovery of Oracle databases. The recovery catalog is opti onal. If you do not use a recovery catalog, RMAN uses the target control file as the sole repository of metadata.
See Also: recovery catalog dat abase
An Oracle database that contains a recovery catalog schema. You should not store the recovery catalog in the target database.
A utility that backs up, restores, and recovers Oracle databases. You can use it with or without the central information repository called a recovery catalog. If you do not use a recovery catalog, RMAN uses the database's control file t o store information necessary for backup and recovery operations. You can use RMAN in conjunction with a media manager to back up fil es to tertiary storage.
See Also: backup piece, backup set, copy, media manager, recovery catalog
One or more tablespaces that are being recovered to an earlier point in time d uring tablespace point-in-time recovery (TSPITR). After TSPITR, all d atabase objects in the recovery set have been recovered to the same point in time.
See Also: auxiliary set
A recovery window is a period of time in a retention pol icy bounded by the current time and the earliest point of recoverability. The point of recoverability is the end time for a hypotheti cal point-in-time recovery, that is, the point to which you must be able to recover following a media failure. A retention policy sta tes that you must have enough backups and archived redo logs to be able to recover to any point between the current time and the poin t of recoverability.
See Also: < strong class="Bold">retention policy
A redo log can be either an online redo log or an archived redo log. The online redo log is a set of two or more redo log group s that records all changes made to Oracle datafiles and control files. An archived redo log is a copy of an online redo log that has been written to an offline destination.
See Also: archived redo log, online redo log
Each online re do log member (which corresponds to an online redo log file) belongs to a group. A group has one or more identical members. A multipl exed redo log is a redo log in which the redo groups have multiple members.
The redo generated by an instance. If the database runs in a single instance configuration, t hen the database has only one thread of redo.
In RMAN, the execution of a REGISTER DATA
BASE command in order to record the existence of a target database in the recovery catalog. A target database is uniquely iden
tified in the catalog by its DBID. You can register more than one database in the same catalog, and also register the same database i
n multiple catalogs.
See Also: < strong class="Bold">DBID
The RMAN metadata about backup and recovery operations on the target database. Either the control file or the recovery catalog can f unction as the RMAN repository.
See Also: recovery catalog
A method for opening a database that archives any current online redo logs (if using ARCHIVELOG mode), resets the log sequence number to 1, clears the online redo logs, and begins a new database incarnation. A database must be opened wi th the RESETLOGS keyword after incomplete recovery or recovery with a backup control file.
The replacement of a lost or damaged file with a backup. You can restore files eit
her with commands such as UNIX cp or the RMAN RESTORE command.
The operation that updates the recovery catalog with current information f
rom the target database control file. You can initiate a full resynchronization of the catalog by issuing a RESYNC CATALOG command. A partial resynchronization transfers information to the recovery catalog about archived redo logs, backup sets a
nd datafile copies. RMAN performs resynchronizations automatically when needed.
A user-defined policy for determining how long backups and archived logs need to be
retained for media recovery. You can define a retention policy in terms of backup redundancy or a
Database segments that record the before-images of changes to the database.
The use of rollback segments to undo uncommitted tran sactions applied to the database during the rolling forward stage of recover.
The application of redo records or incremental backups to datafiles and control files in ord er to recover changes to those files.
See Also: recover, rolling back
System Backup to Tape
A copy of a database's control file taken in an operating system specific location by Recovery Manager. RMAN uses the snapshot control file to read a consistent version of a cont rol file when either resynchronizing the recovery catalog or backing up the control file.
A sequence of RMAN commands sto red in the recovery catalog.
A stamp that defines a committed version of a database at a p oint in time. Oracle assigns every committed transaction a unique SCN.
The SYSTEM tablespace differs from other tablespaces in that all datafiles cont
ained in the tablespace must be online for Oracle to function. If a media failure affects one of the datafiles in SYSTEM
, then you must mount the database and recover.
The recovery of one or more non-SYSTEM tablespaces to a noncurrent time. You
can use either RMAN or user-managed methods to perform TSPITR.
In RMAN, the database that you are backing up or restoring.
A file that belongs to a temporary tablespace, and is created with the TEMP
FILE option. Temporary tablespaces cannot contain permanent database objects such as tables, and are typically used for sortin
g. Because tempfiles cannot contain permanent objects, RMAN does not back them up.
The incomplete recovery of database files to a noncurrent time. Time-based rec overy is also known as point-in-time recovery.
See Also: incomplete recovery, media recovery, recover< /a>
A feature that tran sports a set of tablespaces from one database to another, or from one database to itself. Transporting or "plugging" a tablespace int o a database is like creating a tablespace with preloaded data.
A dedicated tablespaces that stores only undo information when the database is run in automatic undo management mode.
Backups made using a non-RMAN method, for example, using an operating system ut
ility. For example, you can make a user-managed backup by running the cp command on UNIX or the copy comman
d on Windows. A user-managed backup is also called an operating system backups.
A ba
ckup and recovery strategy for an Oracle database that does not use RMAN. This term is equivalent to operating system backup and recovery. You can back up and restore database files using operating syst
em utilities (for example, the cp command in UNIX), and recover using the SQL*Plus RECOVER command.
A test that checks whether a backup can be r estored. RMAN scans the backups and looks at the checksum to verify that the contents can be successfully restored.
See Also: crosscheck, media manager, recovery catalog
A backup of the control file and all datafiles that belong to a database.
See Also: backup
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