当spfile损坏，而且没有了pfile文件和init.ora文件，则我们不得不重建参数文件：
下面模拟参数文件损坏，删除了所有的参数文件：
SQL> startup nomount;
ORA-01078: failure in processing system parameters
LRM-00109: ???????????????????????? ‘/u01/app/oracle/product/11.2.0/dbhome_1/dbs/initorcl3939.ora‘
下面通过alert日志创建了pfile：
SQL> startup nomount;
ORACLE 例程已经启动。
Total System Global Area 422670336 bytes
Fixed Size 1336960 bytes
Variable Size 260049280 bytes
Database Buffers 155189248 bytes
Redo Buffers 6094848 bytes
SQL> create spfile from pfile;
文件已创建。
摘自alert：
processes = 150
memory_target = 404M
control_files = "/u01/app/oracle/oradata/orcl3939/control01.ctl"
control_files = "/u01/app/oracle/flash_recovery_area/orcl3939/control02.ctl"
control_files = "/u01/app/oracle/oradata/orcl3939/control03.ctl"
db_block_size = 8192
compatible = "11.2.0.0.0"
db_recovery_file_dest = "/u01/app/oracle/flash_recovery_area"
db_recovery_file_dest_size= 3852M
undo_tablespace = "UNDOTBS1"
remote_login_passwordfile= "EXCLUSIVE"
db_domain = "localdomain"
instance_name = "ORCL3939"
service_names = "a,b,c,d"
dispatchers = "(PROTOCOL=TCP) (SERVICE=orcl3939XDB)"
local_listener = "(ADDRESS=(PROTOCOL=TCP)(HOST = localhost.localdomain)(PORT = 1521))"
audit_file_dest = "/u01/app/oracle/admin/orcl3939/adump"
audit_trail = "DB"
db_name = "orcl3939"
open_cursors = 300
diagnostic_dest = "/u01/app/oracle"
trace_enabled = TRUE
所以当参数文件损坏，或者没有pfile，init.ora文件，不用太担心，alter日志里记录了数据库启动创建实例的信息，可以手工创建spfile，过程很简单吧！
下面给给大家做个很有意思的实验，紧紧用db_name创建了实例：
SQL> startup force nomount;
ORACLE 例程已经启动。
Total System Global Area 150667264 bytes
Fixed Size 1335080 bytes
Variable Size 92274904 bytes
Database Buffers 50331648 bytes
Redo Buffers 6725632 bytes
下面摘自alert日志：
Starting up:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options.
Using parameter settings in server-side pfile /u01/app/oracle/product/11.2.0/dbhome_1/dbs/initorcl3939.ora
System parameters with non-default values:
db_name = "orcl3939"
Thu May 07 22:13:34 2015
PMON started with pid=2, OS id=5411
Thu May 07 22:13:34 2015
VKTM started with pid=3, OS id=5413 at elevated priority
VKTM running at (10)millisec precision with DBRM quantum (100)ms
Thu May 07 22:13:34 2015
GEN0 started with pid=4, OS id=5417
Thu May 07 22:13:34 2015
DIAG started with pid=5, OS id=5419
Thu May 07 22:13:34 2015
DBRM started with pid=6, OS id=5421
Thu May 07 22:13:34 2015
PSP0 started with pid=7, OS id=5423
Thu May 07 22:13:34 2015
DIA0 started with pid=8, OS id=5425
......
......
所以我们由上知，在参数文件中，需要最少的参数就是db_name,数据库实例就可以启动了
虽然启动了实例，但是缺少一些参数，没有指定控制文件位置，所以mount状态出现了错误：
SQL> alter database mount;
alter database mount
*
第 1 行出现错误:
ORA-00205: ?????????, ??????, ???????