概要：创建一个实例，实例名为my_ins

步骤概要：
1.设置ORACLE_SID
2.新建pfile:initmy_ins.ora
3.创建实例管理目录：{a,b,c,u}dump
4.启动到nomount

具体步骤：
1.设置ORACLE_SID
 [oracle@dba log]$ cd $ORACLE_HOME/dbs
 [oracle@dba dbs]$ export ORACLE_SID=my_ins

2.新建参数文件
 [oracle@dba dbs]$ vim initmy_ins.ora
  *.audit_file_dest='/u01/oracle/admin/my_ins/adump'
  *.background_dump_dest='/u01/oracle/admin/my_ins/bdump'
  *.compatible='10.2.0.1.0'
  *.core_dump_dest='/u01/oracle/admin/my_ins/cdump'
  *.db_name='my_ins'
  *.sga_target=200M
  *.user_dump_dest='/u01/oracle/admin/my_ins/udump'

3.新建dump文件夹
 [oracle@dba admin]$ mkdir -p  $ORACLE_BASE/admin/$ORACLE_SID/{a,b,c,u}dump

4、启动到nomount并测试
 [oracle@dba dbs]$ sqlplus / as sysdba;
 SYS@my_ins> startup nomount;
  ORACLE instance started.

  Total System Global Area  209715200 bytes
  Fixed Size                  1218532 bytes
  Variable Size              67110940 bytes
  Database Buffers          134217728 bytes
  Redo Buffers                7168000 bytes

 SYS@my_ins> show parameter name;

  NAME                                 TYPE       VALUE
  ------------------------------------    ---------- ------------------------------
  db_file_name_convert            string
  db_name                              string     my_ins
  db_unique_name                   string     my_ins
  global_names                      boolean    FALSE
  instance_name                       string     my_ins
  lock_name_space                    string
  log_file_name_convert             string
  service_names                        string     my_ins