OCP 1Z0 052 123
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occur when a database instance is started and database is opened:
1: SGA is allocated.
2: Control file is read.
3: Redo log files are opened.
4: Instance recovery is started.
5: Background processes are started.
6: Data file headers are checked for consistency.
7: Server parameter file or the initialization parameter file is read.
Which option has the correct order in which these steps occur?
A.7, 1, 5, 2, 3, 6, 4
B.1, 5, 7, 2, 3, 6; step 4 is not required
C.7, 1, 5, 2, 3, 6; step 4 is not required
D.1, 2, 3, 5, 6, 4; step 7 is not required
Answer: C
实例启动必须要先读spfile或pfile
因为是shutdown immediate,所以不需要 Instance recovery
步骤如下
7: Server parameter file or the initialization parameter file is read.
1: SGA is allocated.
5: Background processes are started.
2: Control file is read.
3: Redo log files are opened.
6: Data file headers are checked for consistency.
http://blog.csdn.net/jgmydsai/article/details/28699249
及文档中的说明
http://docs.oracle.com/cd/E11882_01/server.112/e40540/startup.htm#CNCPT1289
How an Instance Is Started
When Oracle Database starts an instance, it performs the following basic steps:
Searches for a server parameter file in a platform-specific default location and, if not found, for a text initialization parameter file (specifying
STARTUP
with theSPFILE
orPFILE
parameters overrides the default behavior)Reads the parameter file to determine the values of initialization parameters
Allocates the SGA based on the initialization parameter settings
Starts the Oracle background processes
Opens the alert log and trace files and writes all explicit parameter settings to the alert log in valid parameter syntax
At this stage, no database is associated with the instance. Scenarios that require a NOMOUNT
state include database creation and certain backup and recovery operations.
See Also:
Oracle Database Administrator's Guide to learn how to manage initialization parameters using a server parameter fileHow a Database Is Mounted
The instance mounts a database to associate the database with this instance. To mount the database, the instance obtains the names of the database control files specified in the CONTROL_FILES
initialization parameter and opens the files. Oracle Database reads the control files to find the names of the data files and the online redo log files that it will attempt to access when opening the database.
In a mounted database, the database is closed and accessible only to database administrators. Administrators can keep the database closed while completing specific maintenance operations. However, the database is not available for normal operations.
If Oracle Database allows multiple instances to mount the same database concurrently, then the CLUSTER_DATABASE
initialization parameter setting can make the database available to multiple instances. Database behavior depends on the setting:
If
CLUSTER_DATABASE
isfalse
(default) for the first instance that mounts a database, then only this instance can mount the database.If
CLUSTER_DATABASE
istrue
for the first instance, then other instances can mount the database if theirCLUSTER_DATABASE
parameter settings are set totrue
. The number of instances that can mount the database is subject to a predetermined maximum specified when creating the database.
See Also:
Oracle Database Administrator's Guide to learn how to mount a database
Oracle Real Application Clusters Administration and Deployment Guide for more information about the use of multiple instances with a single database
How a Database Is Opened
Opening a mounted database makes it available for normal database operations. Any valid user can connect to an open database and access its information. Usually, a database administrator opens the database to make it available for general use.
When you open the database, Oracle Database performs the following actions:
Opens the online data files in tablespaces other than undo tablespaces
If a tablespace was offline when the database was previously shut down (see "Online and Offline Tablespaces"), then the tablespace and its corresponding data files will be offline when the database reopens.
Acquires an undo tablespace
If multiple undo tablespaces exists, then the
UNDO_TABLESPACE
initialization parameter designates the undo tablespace to use. If this parameter is not set, then the first available undo tablespace is chosen.Opens the online redo log files
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