Backup and Recovery

Backup and Recovery

1.	What are the steps involved in Database Startup ?
	Start an instance, Mount the Database and Open the Database.
2.	What are the steps involved in Database Shutdown?
	Close the Database; Dismount the Database and Shutdown the Instance.
3.	What is Restricted Mode of Instance Startup ?
	An instance can be started in (or later altered to be in) restricted mode so that when the database is open connections are limited only to those whose user accounts have been granted the RESTRICTED SESSION system privilege.
4.	What are the different modes of mounting a Database with the Parallel Server?
	Exclusive Mode If the first instance that mounts a database does so in exclusive mode, only that Instance can mount the database. Parallel Mode if the first instance that mounts a database is started in parallel mode, other instances that are started in parallel mode can also mount the database.
5.	What is full backup?
	A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.
6.	Can Full Backup be performed when the database is open?
	No.
7.	What is Partial Backup?
	A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
8.	What Is On-lineRedoLog?
	The On-line Redo Log is a set of tow or more on-line redo files that record all committed changes made to the database. Whenever a transaction is committed, the corresponding redo entries temporarily stores in redo log buffers of the SGA are written to an on-line redo log file by the background process LGWR. The on-line redo log files are used in cyclical fashion.
9.	What is Mirrored on-line Redo Log?
	A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks; changes made to one member of the group are made to all members.
10.	What is Archived Redo Log?
	Archived Redo Log consists of Redo Log files that have archived before being reused.
11.	What are the advantages of operating a database in ARCHIVELOG mode over operating it in NO ARCHIVELOG mode?
	Complete database recovery from disk failure is possible only in ARCHIVELOG mode. Online database backup is possible only in ARCHIVELOG mode.
12.	What is Log Switch?
	The point at which ORACLE ends writing to one online redo log file and begins writing to another is called a log switch.
13.	What are the steps involved in Instance Recovery?
	Rolling forward to recover data that has not been recorded in data files, yet has been recorded in the on-line redo log, including the contents of rollback segments. Rolling back transactions that have been explicitly rolled back or have not been committed as indicated by the rollback segments regenerated in step a. Releasing any resources (locks) held by transactions in process at the time of the failure. Resolving any pending distributed transactions undergoing a two-phase commit at the time of the instance failure.
1. What are the different methods of backing up oracle database? - Logical Backups - Cold Backups - Hot Backups (Archive log)   2. What is a logical backup? Logical backup involves reading a set of database records and writing them into a file. Export utility is used for taking backup and Import utility is used to recover from backup.   3. What is cold backup? What are the elements of it? Cold backup is taking backup of all physical files after normal shutdown of database. We need to take. - All Data files. - All Control files. - All on-line redo log files. - The init.ora file (Optional)   4. What are the different kinds of export backups? Full back - Complete database Incremental - Only affected tables from last incremental date/full backup date. Cumulative backup - Only affected table from the last cumulative date/full backup date.   5. What is hot backup and how it can be taken? Taking backup of archive log files when database is open. For this the ARCHIVELOG mode should be enabled. The following files need to be backed up. All data files. All Archive log, redo log files. On control file.   6. What is the use of FILE option in EXP command? To give the export file name.   7. What is the use of COMPRESS option in EXP command? Flag to indicate whether export should compress fragmented segments into single extents. 8. What is the use of GRANT option in EXP command? A flag to indicate whether grants on database objects will be exported or not. Value is 'Y' or 'N'.   9. What is the use of INDEXES option in EXP command? A flag to indicate whether indexes on tables will be exported.   10. What is the use of ROWS option in EXP command? Flag to indicate whether table rows should be exported. If 'N' only DDL statements for the database objects will be created.   11. What is the use of CONSTRAINTS option in EXP command? A flag to indicate whether constraints on table need to be exported.   12. What is the use of FULL option in EXP command? A flag to indicate whether full database export should be performed.   13. What is the use of OWNER option in EXP command? List of table accounts should be exported.   14. What is the use of TABLES option in EXP command? List of tables should be exported.   15. What is the use of RECORD LENGTH option in EXP command? Record length in bytes.   16. What is the use of INCTYPE option in EXP command? Type export should be performed COMPLETE, CUMULATIVE, INCREMENTAL.   17. What is the use of RECORD option in EXP command? For Incremental exports, the flag indirect whether a record will be stores data dictionary tables recording the export.   18. What is the use of PARFILE option in EXP command? Name of the parameter file to be passed for export.   19. What is the use of ANALYSE ( Ver 7) option in EXP command? A flag to indicate whether statistical information about the exported objects should be written to export dump file.   20. What is the use of CONSISTENT (Ver 7) option in EXP command? A flag to indicate whether a read consistent version of all the exported objects should be maintained.   21. What is use of LOG (Ver 7) option in EXP command? The name of the file which log of the export will be written.   22. What is the use of FILE option in IMP command? The name of the file from which import should be performed.   23. What is the use of SHOW option in IMP command? A flag to indicate whether file content should be displayed or not.   24. What is the use of IGNORE option in IMP command? A flag to indicate whether the import should ignore errors encounter when issuing CREATE commands.   25. What is the use of GRANT option in IMP command? A flag to indicate whether grants on database objects will be imported.   26. What is the use of INDEXES option in IMP command? A flag to indicate whether import should import index on tables or not.   27. What is the use of ROWS option in IMP command? A flag to indicate whether rows should be imported. If this is set to 'N' then only DDL for database objects will be executed.