SPFILE 、PFILE 的全面解读

这里先阐述一下数据库的启动过程：

1.      启动实例/例程（nomount状态）时，读取参数文件(文本文件PFILE 或服务器参数文件SPFILE)，分配SGA、启动后台进程、打开告警文件及后台进程跟踪文件；

2.      装载数据库（mount 状态）时，根据初始化参数control_file 的值定位并打开控制文件，从中得到数据文件及重做日志的信息。

3.      打开数据库（open状态）时，打开所有数据文件和重做日志文件；至此，用户可以正常访问数据库；

启动数据库语法：

startup [nomount|mount|open|force] [resrict]  [pfile=filename]

参数文件是实例启动首先要用到的文件，所以此类文件相当关键，本文就结合官方文档对参数文件进行一次全面的解读；

Managing InitializationParameters Using a Server Parameter File

Initializationparameters for the Oracle Database have traditionally been stored in a textinitialization parameter file. For better manageability, you can choose tomaintain initialization parameters in a binary server parameter file that ispersistent across database startup and shutdown. This section introduces theserver parameter file, and explains how to manage initialization parametersusing either method of storing the parameters. The following topics arecontained in this section.

ORACLE DATABASE 初始化变量传统上存放在一个“文本”初始化变量文件中；为了更好的管理，你也可以把初始化变量保存在一个二进制服务器变量文件中，此文件能够永久保存这些变量；

·        What Is a Server Parameter File?

·        Migrating to a Server Parameter File

·        Creating a Server Parameter File

·        The SPFILE Initialization Parameter

·        Changing Initialization Parameter Values

·        Clearing Initialization Parameter Values

·        Exporting the Server Parameter File

·        Backing Up the Server Parameter File

·        Recovering a Lost or Damaged Server Parameter File

·        Viewing Parameter Settings

What Is a ServerParameter File?

A serverparameter file can be thought of as a repository for initialization parametersthat is maintained on the system running the Oracle Database server. It is, bydesign, a server-side initialization parameter file. Initialization parametersstored in a server parameter file are persistent, in that any changes made to the parameters whilean instance is running can persistacrossinstanceshutdown and startup.This arrangementeliminates the need to manually update initialization parameters to makepersistent any changes effected by ALTERSYSTEM statements. It alsoprovides a basis for self-tuning by the Oracle Database server.

A serverparameter file is initially built from a text initialization parameter fileusing the CREATESPFILE statement.(It can also be created directly by the Database Configuration Assistant.) Theserver parameter file is a binary file that cannot be edited using a texteditor.Oracle Database provides other interfaces for viewing and modifyingparameter settings in a server parameter file.

Caution:

Although youcan open the binary server parameter file with a text editor and view its text, do not manually edit it. Doing so willcorrupt the file. You will not be able to start your instance, and if theinstance is running, it could fail.

When youissue a STARTUP command with no PFILE clause, the Oracle instance searches an operatingsystem–specificdefault location for a server parameter filefrom which to read initialization parameter settings. If no serverparameter file is found, the instance searches for a text initializationparameter file. If a server parameter file exists but you want to override it withsettings in a text initialization parameter file, you must specify the PFILE clause when issuing theSTARTUP command. Instructions for starting an instance using a serverparameter file are contained in "Starting Up a Database".

服务器变量文件用createspfile语句从一个文本型的初始化变量文件中创建（也可以用数据库配置助手直接创建），该文件是二进制类型，不能用文本编辑器修改；但是oracledatabase提供了其他查看和修改spfile中参数设置的接口；

注意：尽管可以用文本编辑器打开并浏览这个二进制服务器文件，不要去编辑，否则会破坏掉该文件，如果数据库处于关闭状态，那么将不能启动，如果处在打开状态，那么将不能运行；

执行数据库启动命令startup时，如果没有指定 PFILE子句，首先实例会搜索相应的操作系统指定的服务器变量文件的默认位置（因为不同的操作系统默认位置可能不一样）并从中读取初始化参数设置。如果找不到，再搜索文本类型的初始化参数文件。假设服务器参数文件存在，但是你想用文本型的初始化参数文件来覆盖它，那么在执行startup命令时必须指定PFILE子句；

Migrating to a Server Parameter File

If you arecurrently using a text initialization parameter file, then use the followingsteps to migrate to a server parameter file.

以下步骤用来由文本初始化参数文件迁移成为一个服务器参数

1.   If the initialization parameter file is located on a clientsystem, then transfer the file (for example, FTP) from the client system to theserver system.

Note:

If you are migrating toa server parameter file in an Oracle Real Application Clusters environment, youmust combine all of your instance-specific initialization parameter files intoa single initialization parameter file. Instructions for doing this and otheractions unique to using a server parameter file for instances that are part ofan Oracle Real Application Clusters installation are discussed in Oracle Real Application Clusters Administration and Deployment Guide and in your platform-specific OracleReal Application Clusters Installation Guide.

2.   Create a server parameter file in the default location using the CREATE SPFILEFROM PFILE statement.See "Creating a Server Parameter File" for instructions.

Thisstatement reads the text initialization parameter file to create a serverparameter file. The database does not have to be started to issue a CREATE SPFILE statement.

3.   Start up or restart the instance.

The instancefinds the new SPFILE in the default location and starts up with it.

Creating a ServerParameter File

You use the CREATESPFILE statement tocreate a server parameter file. You must have the SYSDBA or the SYSOPER system privilege to execute this statement.

可以使用 create  spfile from  pfile语句创建服务器参数文件，这时你需要拥有SYSDBA或SYSOPER系统权限；

Note:

When you usethe Database Configuration Assistant to create a database, it automaticallycreates a server parameter file for you.

创建数据库时如果用了DBCA，那么会自动创建一个spfile文件；

The CREATE SPFILE statement can be executed before or after instance startup.However, if the instance has been started using a server parameter file, anerror is raised if you attempt to re-create the same server parameter file thatis currently being used by the instance.

create spfile 语句可以在实例启动前或启动后创建；然而，如果实例已经以spfile启动，如果你试图重建当前正在使用的spfile文件，那么会出现错误(ORA-32002错误)；

例子：

SQL> show parameterspfile

NAME                                 TYPE        VALUE

----------------------------------------------- -------------  -----------------

spfile                               string      E:\ORACLE\PRODUCT\10.2.0\DB_1\DATABASE\SPFILEORCL.ORA

SQL> create spfilefrom pfile;

create spfile frompfile

*

第 1 行出现错误:

ORA-32002: 无法创建已由实例使用的 SPFILE

官方对此的解释及解决方案：

ORA-32002: cannot create SPFILE alreadybeing used by the instance

Cause: A create spfile command is tryingto write to an SPFILE that was used to startup the instance.

Action: Specify a different SPFILE name

You cancreate a server parameter file (SPFILE) from an existing text initialization parameterfile or from memory. Creating the SPFILE from memory means copying the currentvalues of initialization parameters in the running instance to the SPFILE.

你可以从已有的文本初始化参数文件或内存来创建一个spfile文件，从内存创建spfile意味着拷贝当前运行实例的初始参数的当前值到spfile中；

Thefollowing example creates a server parameter file from text initializationparameter file /u01/oracle/dbs/init.ora. In thisexample no SPFILE name is specified, so the file is created with theplatform-specific default name and location shown in Table 2-3.

使用默认的spfile 命名规则及默认路径来创建spfile；

CREATE SPFILE FROM PFILE='/u01/oracle/dbs/init.ora';

The nextexample illustrates creating a server parameter file and supplying a name andlocation.

使用自定义的spfile 命名方法及自定义的路径创建spfile;

CREATE SPFILE='/u01/oracle/dbs/test_spfile.ora'

       FROM PFILE='/u01/oracle/dbs/test_init.ora';

The nextexample illustrates creating a server parameter file in the default locationfrom the current values of the initialization parameters in memory.

在默认路径下以默认的命名方式从内存创建spfile;

CREATE SPFILE FROM MEMORY;

Whether youuse the default SPFILE name and default location or specify an SPFILE name andlocation, if an SPFILE of the same name already exists in the location, it isoverwritten without a warning message.

无论是默认位置还是你指定的位置，如果相同名字的spfile存在，在创建spfile的时候，会无告警情况下进行覆盖；

When youcreate an SPFILE from a text initialization parameter file, comments specifiedon the same lines as a parameter setting in the initialization parameter fileare maintained in the SPFILE. All other comments are ignored.

Oraclerecommends that you allow the database to give the SPFILE the default name andstore it in the default location. This eases administration of your database.For example, the STARTUP command assumes this default location to read the SPFILE.

oracle 建议在默认的位置用默认的命名规则创建spfile，这将有利于管理数据库，例如：在执行startup命令时会到默认的位置读取spfile文件；

Table 2-3 showsthe default name and location for both the text initialization parameter file(PFILE) and server parameter file (SPFILE) for the UNIX, Linux, and Windowsplatforms, both with and without the presence of Oracle Automatic StorageManagement (Oracle ASM). The table assumes that the SPFILE is a file. If it isa raw device, the default name could be a logical volume name or partitiondevice name, and the default location could differ.

Table 2-3 PFILE and SPFILE Default Names and Locations on UNIX,LInux, and Windows

Platform	PFILE Default Name	SPFILE Default Name	PFILE Default Location	SPFILE Default Location
UNIX and Linux	initORACLE_SID.ora	spfileORACLE_SID.ora	OH/dbs or the same location as the datafilesFoot 1	Without Oracle ASM: OH/dbs or the same location as the datafilesFootref 1 When Oracle ASM is present: In the same disk group as the datafilesFoot 2
Windows	initORACLE_SID.ora	spfileORACLE_SID.ora	OH\database	Without Oracle ASM: OH\database When Oracle ASM is present: In the same disk group as the datafilesFootref 2

^Footnote 1 OH representsthe Oracle home directory

^Footnote 2 Assumesdatabase created with DBCA

Note:

Uponstartup, the instance first searches for an SPFILE named spfileORACLE_SID.ora, and if notfound, searches forspfile.ora. Using spfile.ora enables all Real Application Cluster (Oracle RAC) instances touse the same server parameter file.

If neither SPFILE isfound, the instance searches for the text initialization parameter file initORACLE_SID.ora.

If youcreate an SPFILE in a location other than the default location, you must createin the default PFILE location a "stub" PFILE that points to the serverparameter file. For more information, see "Starting Up a Database" or  this :

启动实例时，首先搜索以默认命名规则（类似spfileORACLE_SID.ora）的spfile，如果没有，再找 spfile.ora 。用spfile.ora使所有的oracle RAC实例使用同一个服务器参数文件；如果spfile.ora也没有找到，那么会搜索文本类型的参数文件initORACLE_SID.ora

如果你在非默认位置创建spfile ,那么你必须在默认pfile位置创建一个指向spfile的“stub”PFILE，看这：

{

NondefaultServer Parameter Files A nondefault serverparameter file (SPFILE) is an SPFILE that is in a location other than the default location. It is notusually necessary to start an instance with a nondefault SPFILE. However,should such a need arise, both SRVCTL (with Oracle Restart) and SQL*Plusprovide ways to do so. These are described later in this section.

Initialization Filesand Oracle Automatic Storage Management A databasethat uses Oracle Automatic Storage Management (Oracle ASM) usually has anondefault SPFILE. If you usethe Database Configuration Assistant (DBCA) to configure a database to useOracle ASM, DBCA creates an SPFILE for the database instance in an Oracle ASM disk group, and thencauses a text initialization parameter file (PFILE) to be created in thedefault location in the local file system to point to the SPFILE, asexplained in the next section.

Starting Up withSQL*Plus with a Nondefault Server Parameter File

WithSQL*Plus you can use the PFILE clause to start an instance with a nondefault server parameterfile.

To start up with SQL*Plus with a nondefault server parameterfile:

1.   Create a one-line text initialization parameter file thatcontains only the SPFILE parameter. The value of the parameter is the nondefault serverparameter file location.

For example,create a text initialization parameter file /u01/oracle/dbs/spf_init.ora that contains only the following parameter:

SPFILE = /u01/oracle/dbs/test_spfile.ora

Note:

You cannot use the IFILE initialization parameter within a text initialization parameterfile to point to a server parameter file. In this context, you must use the SPFILE initialization parameter.

2.   Start up the instance pointing to this initialization parameterfile.

3.  STARTUP PFILE = /u01/oracle/dbs/spf_init.ora

The SPFILE must reside on the database host computer. Therefore, thepreceding method also provides a means for a client system to start a databasethat uses an SPFILE. It alsoeliminates the need for a client system to maintain a client-sideinitialization parameter file. When the client system reads the initializationparameter file containing the SPFILE parameter, it passes the value to the server where the specified SPFILE is read.

}

When youcreate the database with DBCA when Oracle ASM is present, DBCA places theSPFILE in an Oracle ASM disk group, and also causes this stub PFILE to becreated.

The SPFILE Initialization Parameter

The SPFILE initialization parameter contains the name of the current serverparameter file. When the default server parameter file is used by thedatabase—that is, you issue a STARTUP command and do not specify a PFILE parameter—the value of SPFILE is internally set by the server. TheSQL*Plus command SHOWPARAMETERS SPFILE (or anyother method of querying the value of a parameter) displays the name of theserver parameter file that is currently in use.

初始化参数spfile 包含了当前服务器参数文件的名称，如果数据库使用默认的服务器参数文件，那么在startup命令中没有指定pfile参数，spfile 被服务器设置； sql* plus命令showparameter spfile会列出当前使用的服务器参数文件的名字及路径；

Changing InitializationParameter Values

The ALTERSYSTEM statementenables you to set, change, or restore to default the values of initializationparameters. If you are using a text initialization parameter file, the ALTER SYSTEM statement changes the value of a parameter only for the currentinstance, because there is no mechanism for automatically updating textinitialization parameters on disk. You must update them manually to be passedto a future instance. Using a server parameter file overcomes this limitation.

alter  system 语句可以设置、修改、或恢复初始参数的默认值；如果正用文本型的初始参数文件，该命令仅仅修改当前实例的参数的值，因为没有自动更新磁盘上初始参数的机制；你必须手动修改才可以；用服务器参数文件可以避免此限制；

There aretwo kinds of initialization parameters:

·        Dynamic initializationparameters can bechanged for the current Oracle Database instance. The changes take effectimmediately.

·        Static initializationparameters cannot bechanged for the current instance. You must change these parameters in the textinitialization file or server parameter file and then restart the databasebefore changes take effect.

有两种初始化参数：

1.    动态初始化参数可以对当前实例修改，并立即生效；

2.   静态初始化参数不能对当前实例修改，你必须在文本初始化文件中或服务器参数文件中修改后重启数据库才能生效；

Setting orChanging Initialization Parameter Values

Use the SET clause of the ALTERSYSTEM statement toset or change initialization parameter values. The optional SCOPE clause specifies the scope of a change as described in thefollowing table:

SCOPE Clause	Description
SCOPE = SPFILE	The change is applied in the server parameter file only. The effect is as follows: 修改只应用到spfile中 ·         No change is made to the current instance. 不会更改当前实例 ·         For both dynamic and static parameters, the change is effective at the next startup and is persistent. 动态和静态参数，改变都会在下次启动后生效且具有永久性； This is the only SCOPE specification allowed for static parameters. 只有该语句能够修改静态参数
SCOPE = MEMORY	The change is applied in memory only. The effect is as follows: 仅仅反映到memory中；对当前实例有效；重启后失效；且不能修改静态参数； ·         The change is made to the current instance and is effective immediately. ·         For dynamic parameters, the effect is immediate, but it is not persistent because the server parameter file is not updated. For static parameters, this specification is not allowed.
SCOPE = BOTH	The change is applied in both the server parameter file and memory. The effect is as follows: 上面两种的结合；  但是不能修改静态参数； ·         The change is made to the current instance and is effective immediately. ·         For dynamic parameters, the effect is persistent because the server parameter file is updated. For static parameters, this specification is not allowed.

It is anerror to specify SCOPE=SPFILE or SCOPE=BOTH if the instance did not start up with a server parameter file.The default is SCOPE=BOTH if a server parameter file was used to start up the instance,and MEMORY if a text initialization parameter file was used to start up theinstance.

启动时如果没有使用spfile，那么当修改是用了scopt=spfile或 scopt=both那么就会报错（ora-32001）；

例子：

SQL> show parameterspfile

NAME                                 TYPE        VALUE

----------------------------------------------- ---------------- --------------

spfile                               string      E:\ORACLE\PRODUCT\10.2.0\DB_1\DATABASE\SPFILEORCL.ORA

SQL> show parameteruser_dump

NAME                                 TYPE        VALUE

----------------------------------------------- ----------------- -------------

user_dump_dest                       string     E:\ORACLE\PRODUCT\10.2.0\ADMIN\ORCL\UDUMP

SQL> create pfile='d:\pfile.ora'from spfile;

文件已创建。

SQL> shutdownimmediate;

数据库已经关闭。

已经卸载数据库。

ORACLE 例程已经关闭。

SQL> startuppfile='d:\pfile.ora';

ORACLE 例程已经启动。

Total System GlobalArea  838860800 bytes

Fixed Size                  1293384 bytes

Variable Size             734004152 bytes

Database Buffers           96468992 bytes

Redo Buffers                7094272 bytes

数据库装载完毕。

数据库已经打开。

SQL> alter systemset user_dump_dest='e:\oracle\product\10.2.0'scope=both;

alter system setuser_dump_dest='e:\oracle\product\10.2.0' scope=both

*

第 1 行出现错误:

ORA-32001: 已请求写入 SPFILE,但是在启动时未指定 SPFILE

SQL> alter systemset user_dump_dest='e:\oracle\product\10.2.0'scope=spfile;

alter system setuser_dump_dest='e:\oracle\product\10.2.0' scope=spfile

*

第 1 行出现错误:

ORA-32001: 已请求写入 SPFILE,但是在启动时未指定 SPFILE

SQL> alter systemset user_dump_dest='e:\oracle\product\10.2.0' scope=memory;

系统已更改。

SQL> show parameteruser_dump

NAME                                 TYPE        VALUE

----------------------------------------------- ----------------- -------------

user_dump_dest                       string     E:\ORACLE\PRODUCT\10.2.0

SQL> create spfilefrom pfile;

create spfile frompfile

*

第 1 行出现错误:

ORA-01078: 处理系统参数失败

LRM-00109: could notopen parameter file

'E:\ORACLE\PRODUCT\10.2.0\DB_1\DATABASE\INITORCL.ORA'

SQL> create spfilefrom pfile='d:\pfile.ora';

文件已创建。

SQL> shutdownimmediate;

数据库已经关闭。

已经卸载数据库。

ORACLE 例程已经关闭。

SQL> startup

ORACLE 例程已经启动。

Total System GlobalArea  838860800 bytes

Fixed Size                  1293384 bytes

Variable Size             734004152 bytes

Database Buffers           96468992 bytes

Redo Buffers                7094272 bytes

数据库装载完毕。

数据库已经打开。

SQL> show parameteruser_dump

NAME                                 TYPE        VALUE

----------------------------------------------- ----------------- -------------

user_dump_dest                       string     E:\ORACLE\PRODUCT\10.2.0\ADMIN\ORCL\UDUMP

官方解释及解决方案：

ORA-32001: write to SPFILE requested butno SPFILE is in use

Cause: An ALTER SYSTEM command or aninternal self-tuning mechanism requested a write to the SPFILE but no SPFILEwas in use.

Action: Re-start the instance using anSPFILE, or execute ALTER SYSTEM SET SPFILE.

For dynamicparameters, you can also specify the DEFERRED keyword. When specified, the change is effective only for futuresessions.

对于动态参数，可以指定deferred参数，只对接下来的会话有效；

When youspecify SCOPE as SPFILE or BOTH, anoptional COMMENT clause lets you associate a text string with the parameterupdate. The comment is written to the server parameter file.

当scope指定spfile或both时，可以为修改的参数添加注释；

Thefollowing statement changes the maximum number of failed login attempts beforethe connection is dropped. It includes a comment, and explicitly states thatthe change is to be made only in the server parameter file.

ALTER SYSTEM SET SEC_MAX_FAILED_LOGIN_ATTEMPTS=3

                 COMMENT='Reduce from 10 for tighter security.'

                 SCOPE=SPFILE;

The nextexample sets a complex initialization parameter that takes a list ofattributes. Specifically, the parameter value being set is the LOG_ARCHIVE_DEST_ninitializationparameter. This statement could change an existing setting for this parameteror create a new archive destination.

ALTER SYSTEM 

     SET LOG_ARCHIVE_DEST_4='LOCATION=/u02/oracle/rbdb1/',MANDATORY,'REOPEN=2'

         COMMENT='Add new destination on Nov 29'

         SCOPE=SPFILE;

When a valueconsists of a list of parameters, you cannot edit individual attributes by theposition or ordinal number. You must specify the complete list of values eachtime the parameter is updated, and the new list completely replaces the oldlist.

如果一个值由多个参数组成，那么修改的时候必须全部指定，有一样的就再写一次；

ClearingInitialization Parameter Values

You can usethe ALTER SYSTEM RESET command to clear (remove) the setting of any initializationparameter in the SPFILE that was used to start the instance. Neither SCOPE=MEMORY nor SCOPE=BOTH are allowed. The SCOPE = SPFILE clause is not required, but can be included.

You may wantto clear a parameter in the SPFILE so that upon the next database startup adefault value is used.

See Also:

Oracle Database SQL Language Reference for information about the ALTER SYSTEM command

Exporting theServer Parameter File

You can usethe CREATEPFILE statement toexport a server parameter file (SPFILE) to a text initialization parameterfile. Doing so might be necessary for several reasons:

·        For diagnostic purposes, listing all of the parameter valuescurrently used by an instance. This is analogous to the SQL*Plus SHOWPARAMETERS command orselecting from the V$PARAMETER or V$PARAMETER2 views.

·        To modify the &spfile;server parameter file by firstexporting it, editing the resulting text file, and then re-creating it usingthe CREATESPFILE statement

有几个原因使你用create pfile语句导出spfile 文件到一个文本初始化参数文件中：诊断的目的，列出所有当前实例使用的参数值，类似于sql*plus的show parameter命令或从v$parameter或v$parameter2视图中查询语句；修改spfile文件，修改好之后可以通过create spfile语句重建服务器参数文件；

The exportedfile can also be used to start up an instance using the PFILE clause.

被导出的文本型参数文件也可以在startup的命令中以pfile子句指定，以用来启动实例；

You musthave the SYSDBA or the SYSOPER system privilege to execute the CREATE PFILE statement. The exported file is created on the database serversystem. It contains any comments associated with the parameter in the same lineas the parameter setting.

Thefollowing example creates a text initialization parameter file from the SPFILE:

CREATE PFILE FROM SPFILE;

Because nonames were specified for the files, the database creates an initializationparameter file with a platform-specific name, and it is created from theplatform-specific default server parameter file.

Thefollowing example creates a text initialization parameter file from a serverparameter file, but in this example the names of the files are specified:

CREATE PFILE='/u01/oracle/dbs/test_init.ora'

       FROM SPFILE='/u01/oracle/dbs/test_spfile.ora';

Note:

Analternative is to create a PFILE from the current values of the initializationparameters in memory. The following is an example of the required command:

CREATE PFILE='/u01/oracle/dbs/test_init.ora' FROM MEMORY;

Backing Up theServer Parameter File

You cancreate a backup of your server parameter file (SPFILE) by exporting it, asdescribed in "Exporting the Server Parameter File".If the backup and recovery strategy for your database is implemented usingRecovery Manager (RMAN), then you can use RMAN to create a backup of theSPFILE. The SPFILE is backed up automatically by RMAN when you back up yourdatabase, but RMAN also enables you to specifically create a backup of thecurrently active SPFILE.

See Also:

Oracle Database Backup and Recovery User's Guide

Recovering a Lostor Damaged Server Parameter File

If yourserver parameter file (SPFILE) becomes lost or corrupted, the current instancemay fail, or the next attempt at starting the database instance may fail. Thereare several ways to recover the SPFILE:

如果初始化参数文件丢失或损坏，那么需要恢复，否则实例将失败；下面是几种恢复spfile的方法：

·        If the instance is running, issue the following command tore-create the SPFILE from the current values of initialization parameters inmemory:

如果实例在运行，那么用下面的语句来重建；

·         CREATE SPFILE FROM MEMORY;

This commandcreates the SPFILE with the default name and in the default location. You canalso create the SPFILE with a new name or in a specified location. See "Creating a Server Parameter File" for examples.

·        If you have a valid text initialization parameter file (PFILE),re-create the SPFILE from the PFILE with the following command:

如果你有可用的pfile ,那么用下列语句来重建spfile;

·         CREATE SPFILE FROM PFILE;

This commandassumes that the PFILE is in the default location and has the default name. See "Creating a Server Parameter File" for the command syntax to use when thePFILE is not in the default location or has a nondefault name.

·        Restore the SPFILE from backup.

从备份中恢复；

See "Backing Up the Server Parameter File" for more information.

·        If none of the previous methods are possible in your situation,perform these steps:

1.   Create a text initialization parameter file (PFILE) from theparameter value listings in the alert log.

When aninstance starts up, the initialization parameters used for startup are writtento the alert log. You can copy and paste this section from the text version ofthe alert log (without XML tags) into a new PFILE.

See "Viewing the Alert Log" for more information.

2.   Create the SPFILE from the PFILE.

See "Creating a Server Parameter File" for instructions.

如果以上发放均不适合你的状况，那么执行这些步骤来恢复吧：

1.   从alter log中列出的变量值创建一个pfile文件；（实例启动时，这些启动时使用的初始化参数会写进alert log里，你可以拷贝过来用）

2.   再用createspfile from pfile创建spfile ;

Read/Write Errors During a Parameter Update

If an erroroccurs while reading or writing the server parameter file during a parameterupdate, the error is reported in the alert log and all subsequent parameterupdates to the server parameter file are ignored. At this point, you can takeone of the following actions:

·        Shut down the instance, recover the server parameter file anddescribed earlier in this section, and then restart the instance.

·        Continue to run the database if you do not care that subsequentparameter updates will not be persistent.

Viewing ParameterSettings

You can viewparameter settings in several ways, as shown in the following table.

Method	Description
SHOW PARAMETERS	This SQL*Plus command displays the values of initialization parameters in effect for the current session.
SHOW SPPARAMETERS	This SQL*Plus command displays the values of initialization parameters in the server parameter file (SPFILE).
CREATE PFILE	This SQL statement creates a text initialization parameter file (PFILE) from the SPFILE or from the current in-memory settings. You can then view the PFILE with any text editor.
V$PARAMETER	This view displays the values of initialization parameters in effect for the current session.
V$PARAMETER2	This view displays the values of initialization parameters in effect for the current session. It is easier to distinguish list parameter values in this view because each list parameter value appears in a separate row.
V$SYSTEM_PARAMETER	This view displays the values of initialization parameters in effect for the instance. A new session inherits parameter values from the instance-wide values.
V$SYSTEM_PARAMETER2	This view displays the values of initialization parameters in effect for the instance. A new session inherits parameter values from the instance-wide values. It is easier to distinguish list parameter values in this view because each list parameter value appears in a separate row.
V$SPPARAMETER	This view displays the current contents of the SPFILE. The view returns FALSE values in the ISSPECIFIEDcolumn if an SPFILE is not being used by the instance.