Oracle: DATABASE OPERATION, BACKUP AND RECOVERY

DATABASE OPERATION, BACKUP AND RECOVERY
137. What are the steps involved in Database Startup ?
Start an instance, Mount the Database and Open the Database.
138. What are the steps involved in Database Shutdown ?
Close the Database, Dismount the Database and Shutdown the Instance.
139. 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.
140. 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.
141. 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.
142. Can Full Backup be performed when the database is open ?
No.
143. 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.
144.WhatisOn-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.
145. 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.
146. What is Archived Redo Log ?
Archived Redo Log consists of Redo Log files that have archived before being reused.
147. 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.
148. 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.
149. What are the steps involved in Instance Recovery ?
R_olling 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.