Oracle的启动过程

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Oracle的启动过程共经历四个阶段：

shutdown→nomount→mount→open

shutdown→nomount过程：

                      读初始参数文件
                      分配物理内存
                      启动后台进程
                      定位到控制文件
                      打开/写alert文件
   nomount过程可以访问的动态性能视图：v$parameter,v$sga,v$option,v$process,v$version,v$instance
nomount→mount过程：

                      打开控制文件
                   确认 database的结构信息
   mount过程可以访问的动态性能视图: v$thread,v$controlfile,v$database,v$datafile,v$datafile_header,v$logfile
   以下任务必须在mount状态下进行：

                           命名数据文件
                          启用和禁用重作日志归档选项
                          执行完全数据库恢复
mount→open过程：

打开数据文件
打开重做日志文件
最后阶段中，oracle服务器验证所有数据文件和重做日志文件是否可以打开，并检查数据库的一致性，如果需要，smon进程会启动例程恢复。

自上而下：

shutdown：

nomount：读取初始化参数，并且分配物理内存，通过初始化参数定位到control file，后台进程启动，写alter文件，如果alter文件不存在将创建它

SQL> startup nomount
ORACLE 例程已经启动。

Total System Global Area 167772160 bytes
Fixed Size                  1247900 bytes
Variable Size              83887460 bytes
Database Buffers           79691776 bytes
Redo Buffers                2945024 bytes

altert文件中内容：

Fri Dec 28 11:34:06 2007
Starting ORACLE instance (normal)
LICENSE_MAX_SESSION = 0
LICENSE_SESSIONS_WARNING = 0
Picked latch-free SCN scheme 2
Using LOG_ARCHIVE_DEST_10 parameter default value as USE_DB_RECOVERY_FILE_DEST
Autotune of undo retention is turned on.
IMODE=BR
ILAT =18
LICENSE_MAX_USERS = 0
SYS auditing is disabled
ksdpec: called for event 13740 prior to event group initialization
Starting up ORACLE RDBMS Version: 10.2.0.1.0.
System parameters with non-default values:
processes                = 150
__shared_pool_size       = 75497472
__large_pool_size        = 4194304
__java_pool_size         = 4194304
__streams_pool_size      = 0
spfile                   = E:/ORACLE/PRODUCT/10.2.0/DB_2/DBS/SPFILEORCL.ORA
sga_target               = 167772160
control_files            = E:/ORACLE/PRODUCT/10.2.0/ORADATA/ORCL/CONTROL01.CTL, E:/ORACLE/PRODUCT/10.2.0/ORADATA/ORCL/CONTROL02.CTL, E:/ORACLE/PRODUCT/10.2.0/ORADATA/ORCL/CONTROL03.CTL
db_block_size            = 8192
__db_cache_size          = 79691776
compatible               = 10.2.0.1.0
db_file_multiblock_read_count= 16
db_recovery_file_dest    = E:/oracle/product/10.2.0/flash_recovery_area
db_recovery_file_dest_size= 2147483648
undo_management          = AUTO
undo_tablespace          = UNDOTBS1
remote_login_passwordfile= EXCLUSIVE
db_domain                =
dispatchers              = (PROTOCOL=TCP) (SERVICE=orclXDB)
job_queue_processes      = 10
audit_file_dest          = E:/ORACLE/PRODUCT/10.2.0/ADMIN/ORCL/ADUMP
background_dump_dest     = E:/ORACLE/PRODUCT/10.2.0/ADMIN/ORCL/BDUMP
user_dump_dest           = E:/ORACLE/PRODUCT/10.2.0/ADMIN/ORCL/UDUMP
core_dump_dest           = E:/ORACLE/PRODUCT/10.2.0/ADMIN/ORCL/CDUMP
db_name                  = orcl
open_cursors             = 300
pga_aggregate_target     = 16777216
PMON started with pid=2, OS id=3280
PSP0 started with pid=3, OS id=2972
MMAN started with pid=4, OS id=2280
DBW0 started with pid=5, OS id=828
LGWR started with pid=6, OS id=1936
CKPT started with pid=7, OS id=3844
SMON started with pid=8, OS id=596
RECO started with pid=9, OS id=3252
CJQ0 started with pid=10, OS id=1932
MMON started with pid=11, OS id=3788
Fri Dec 28 11:34:17 2007
starting up 1 dispatcher(s) for network address '(ADDRESS=(PARTIAL=YES)(PROTOCOL=TCP))'...
MMNL started with pid=12, OS id=928
Fri Dec 28 11:34:17 2007
starting up 1 shared server(s) ...

在nomount状态：
可以访问到实例

SQL> select * from v$instance;

INSTANCE_NUMBER INSTANCE_NAME HOST_NAME
--------------- -------------------------------- -------------------------------
1 orcl ORACLE10G

可以访问到后台进程

select * from v$bgprocess;

可以访问到内存结构

SQL> select * from v$sga;

NAME                                          VALUE
---------------------------------------- ----------
Fixed Size                                  1247900
Variable Size                              83887460
Database Buffers                           79691776
Redo Buffers                                2945024

但不可以访问database结构

SQL> select * from v$database;
select * from v$database
*
第 1 行出现错误:
ORA-01507: ??????

mount：读并打开控制文件，并确认到database的结构信息

SQL> alter database mount
2 /

数据库已更改。

SQL> select * from v$database;

DBID NAME CREATED RESETLOGS_CHANGE# RESETLOGS_TIME PRIOR_RESETLOGS_CHANGE# PRIOR_RESE
---------- --------- -------------- ----------------- --------------
1170053590 ORCL 25-12? -07 534907 25-12? -07 1 30-8? -05 ARCHIVELOG

可以找到有什么样的表空间

SQL> select * from v$tablespace;

       TS# NAME                           INC BIG FLA ENC
---------- ------------------------------ --- --- --- ---
         0 SYSTEM                         YES NO YES
         1 UNDOTBS1                       YES NO YES
         2 SYSAUX                         YES NO YES
         4 USERS                          YES NO YES
         3 TEMP                           NO NO YES
         6 EXAMPLE                        YES NO YES

已选择6行。

有什么样的数据文件组成：

SQL> select * from v$datafile
2 /

FILE# CREATION_CHANGE# CREATION_TIME         TS#     RFILE# STATUS ENABLED    CHECKPOINT_CHANGE# CHECK
------- ---------------- -------------- ---------- ---------- ------- ---------- ----------------
      1                9 30-8? -05              0          1 SYSTEM READ WRITE             777989 28-12? -07
      2           532340 30-8? -05              1          2 ONLINE READ WRITE             777989 28-12? -07
      3             6100 30-8? -05              2          3 ONLINE READ WRITE             777989 28-12? -07
      4             9769 30-8? -05              4          4 ONLINE READ WRITE             777989 28-12? -07
      5           559801 25-12? -07              6          5 ONLINE READ WRITE             777989 28-12? -07

有什么样的日志文件组成：

SQL> select * from v$logfile;
行将被截断

    GROUP# STATUS TYPE    MEMBER
---------- ------- ------- ----------------------------------------------------------
         3         ONLINE E:/ORACLE/PRODUCT/10.2.0/ORADATA/ORCL/REDO03.LOG
         2         ONLINE E:/ORACLE/PRODUCT/10.2.0/ORADATA/ORCL/REDO02.LOG
         1         ONLINE E:/ORACLE/PRODUCT/10.2.0/ORADATA/ORCL/REDO01.LOG

在这个状态用户表还不能打开

open：所有文件被打开，并确认database状态

SQL> alter database open;

数据库已更改。