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oracle 11g bootstrap$系列一

背景

oracle从nomount到mount，内部机制到底是怎么样的，要经历哪些过程，了解这些，对于理解ORACLE，会大有帮助，拓宽分析解决问题能力。

结论

1,测试环境为oracle 11.2.0.1
2,bootstrap$为底层表，共计存储60个对象
3,这60个对象，有表，有索引，也有cluster table
4,obj#为-1及0的对象不在obj$，它的含义如下：

LINE# OBJ# SQL_TEXT
---------- ---------- ----------------------------------------------------------------------------------------------------
-1 -1 8.0.0.0.0
0 0 CREATE ROLLBACK SEGMENT SYSTEM STORAGE ( INITIAL 112K NEXT 56K MINEXTENTS 1 MAXEXTENTS 32765 OBJNO
0 EXTENTS (FILE 1 BLOCK 128))

5，这60个对象全存储在1号文件即system.dbf中
6，通过10046分析，从NOMOUNT到MOUNT,依次是dbwr,ckpt,dbwr,lgwr,ckpt几个后台进程参考了从nomount至mount的工作，
也就是如果这些后台进程出现故障，数据库无法从nomount到mount状态
我是源于10046 TRACE文件中的等待事件rdbms ipc reply
7, 要理解相关几个等待事件的含义及其参数含义
rdbms ipc reply

Disk file operations I/O

control file sequential read

control file heartbeat

control file parallel write

ADR block file read

8，关于这些等待事件，还正在研究中，将于下文进行继续测试
9，关于上述这些等待事件的obj#=-1,其含义还没有搞懂
以及file=0和file=1 或file=2

测试

1,数据库版本
SQL> select * from v$version where rownum=1;

BANNER
--------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.
2.0.1.0 - 64bit Production

2,bootstrap$含义
SQL> desc bootstrap$;
Name Null? Type
----------------------- -------- ----------------
LINE# NOT NULL NUMBER
OBJ# NOT NULL NUMBER
SQL_TEXT NOT NULL VARCHAR2(4000)

3,可见bootstrap$共计存储60个对象
SQL> select distinct obj# from bootstrap$ order by 1;

OBJ#
----------
-1
0
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59

60 rows selected.

4，我们看看这60个对象都是什么呢？
SQL> select obj#,name,type# from obj$ where obj# in (select obj# from bootstrap$) order by 1;

OBJ# NAME TYPE#
---------- -------------------------------------------------- ----------
2 C_OBJ# 3
3 I_OBJ# 1
4 TAB$ 2
5 CLU$ 2
6 C_TS# 3
7 I_TS# 1
8 C_FILE#_BLOCK# 3
9 I_FILE#_BLOCK# 1
10 C_USER# 3
11 I_USER# 1
12 FET$ 2
13 UET$ 2
14 SEG$ 2
15 UNDO$ 2
16 TS$ 2
17 FILE$ 2
18 OBJ$ 2
19 IND$ 2
20 ICOL$ 2
21 COL$ 2
22 USER$ 2
23 PROXY_DATA$ 2
24 I_PROXY_DATA$ 1
25 PROXY_ROLE_DATA$ 2
26 I_PROXY_ROLE_DATA$_1 1
27 I_PROXY_ROLE_DATA$_2 1
28 CON$ 2
29 C_COBJ# 3
30 I_COBJ# 1
31 CDEF$ 2
32 CCOL$ 2
33 I_TAB1 1
34 I_UNDO1 1
35 I_UNDO2 1
36 I_OBJ1 1
37 I_OBJ2 1
38 I_OBJ3 1
39 I_OBJ4 1
40 I_OBJ5 1
41 I_IND1 1
42 I_ICOL1 1
43 I_FILE1 1
44 I_FILE2 1
45 I_TS1 1
46 I_USER1 1
47 I_USER2 1
48 I_COL1 1
49 I_COL2 1
50 I_COL3 1
51 I_CON1 1
52 I_CON2 1
53 I_CDEF1 1
54 I_CDEF2 1
55 I_CDEF3 1
56 I_CDEF4 1
57 I_CCOL1 1
58 I_CCOL2 1
59 BOOTSTRAP$ 2

58 rows selected.

5,看下上述58个对象属于什么类型的对象
摘自dcore.sql文件，可知type#=1为索引，2为表，3为集或叫cluster table(这是一种特殊类型的表)
type# number not null, /* object type (see KQD.H): */
/* 1 = INDEX, 2 = TABLE, 3 = CLUSTER, 4 = VIEW, 5 = SYNONYM, 6 = SEQUENCE, */
/* 7 = PROCEDURE, 8 = FUNCTION, 9 = PACKAGE, 10 = NON-EXISTENT, */
/* 11 = PACKAGE BODY, 12 = TRIGGER, 13 = TYPE, 14 = TYPE BODY, */
/* 19 = TABLE PARTITION, 20 = INDEX PARTITION, 21 = LOB, 22 = LIBRARY, */
/* 23 = DIRECTORY , 24 = QUEUE, */
/* 25 = IOT, 26 = REPLICATION OBJECT GROUP, 27 = REPLICATION PROPAGATOR, */
/* 28 = JAVA SOURCE, 29 = JAVA CLASS, 30 = JAVA RESOURCE, 31 = JAVA JAR, */
/* 32 = INDEXTYPE, 33 = OPERATOR , 34 = TABLE SUBPARTITION, */
/* 35 = INDEX SUBPARTITION */
/* 82 = (Data Mining) MODEL */
/* 92 = OLAP CUBE DIMENSION, 93 = OLAP CUBE */
/* 94 = OLAP MEASURE FOLDER, 95 = OLAP CUBE BUILD PROCESS */

所以可见上述的58个对象有表，也有索引，也有cluster table

6,大家不知注意到没有，出现一个问题，bootstrap$存储了60个对象，但我们上述只说了58个对象，还有2个对象，这2个对象又是什么呢？

可见这2个对象肯定不存储在obj$中
SQL> select obj#,name from obj$ where obj# in (-1,0);
no rows selected

从查询出来的结果可知,-1存储对象为8.0.0.0.0,这是个什么东西呢，0对象为创建一个system rollback segment的ddl语句
SQL> col sql_text for a100
SQL> select line#,obj#,sql_text from bootstrap$ where obj# in (-1,0);

LINE# OBJ# SQL_TEXT
---------- ---------- ----------------------------------------------------------------------------------------------------
-1 -1 8.0.0.0.0
0 0 CREATE ROLLBACK SEGMENT SYSTEM STORAGE ( INITIAL 112K NEXT 56K MINEXTENTS 1 MAXEXTENTS 32765 OBJNO
0 EXTENTS (FILE 1 BLOCK 128))

7，查看上述60个对象所处的文件及数据块

我们仅列举部分，可知60个对象全存储在文件1号中，也就是system表空间的数据文件
SQL> select distinct DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID) file_no from tab$;

FILE_NO
----------
1

SQL> select count(distinct DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)) block_count from tab$;

BLOCK_COUNT
-----------
539

SQL> select distinct DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID) file_no from seq$;

FILE_NO
----------
1

SQL> select count(distinct DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)) block_count from seq$;

BLOCK_COUNT
-----------
3

SQL> select distinct DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID) file_no from col$;

FILE_NO
----------
1

SQL> select count(distinct DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)) block_count from col$;

BLOCK_COUNT
-----------
1157

8，现在重启数据库到nomount,用10046跟踪，看启动是以何种方式及次序读取这些60个对象的？
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup nomount
ORACLE instance started.

Total System Global Area 2137886720 bytes
Fixed Size 2215064 bytes
Variable Size 1409287016 bytes
Database Buffers 721420288 bytes
Redo Buffers 4964352 bytes

SQL> oradebug setmypid
Statement processed.
SQL> oradebug event 10046 trace name context forever,level 12
Statement processed.
SQL> alter database mount;
Database altered.

SQL> oradebug event 10046 trace name context off
Statement processed.
SQL> oradebug tracefile_name
/oracle/diag/rdbms/guowang/guowang/trace/guowang_ora_8301.trc

9,查看上述的trace文件
*** 2015-10-31 09:04:49.823
Oradebug command 'event 10046 trace name context forever,level 12' console output:
WAIT #0: nam='SQL*Net message to client' ela= 4 driver id=1650815232 #bytes=1 p3=0 obj#=-1 tim=1446296689823453

*** 2015-10-31 09:06:12.614
WAIT #0: nam='SQL*Net message from client' ela= 82780553 driver id=1650815232 #bytes=1 p3=0 obj#=-1 tim=1446296772614555
XCTEND rlbk=0, rd_only=1, tim=1446296772631455
=====================
PARSING IN CURSOR #3 len=21 dep=0 uid=0 oct=35 lid=0 tim=1446296772652864 hv=4108919762 ad='de9f8750' sqlid='5fk0qrbufk8yk'
alter database mount
END OF STMT
PARSE #3:c=1000,e=37098,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,plh=0,tim=1446296772652863
WAIT #3: nam='rdbms ipc reply' ela= 61923 from_process=10 timeout=60 p3=0 obj#=-1 tim=1446296772825546
WAIT #3: nam='reliable message' ela= 21968 channel context=3684420096 channel handle=3683986800 broadcast message=3685422768 obj#=-1 tim=1446296772861121

*** 2015-10-31 09:06:12.983
WAIT #3: nam='rdbms ipc reply' ela= 118283 from_process=12 timeout=900 p3=0 obj#=-1 tim=1446296772983943
WAIT #3: nam='Disk file operations I/O' ela= 138 FileOperation=2 fileno=0 filetype=1 obj#=-1 tim=1446296772993312
WAIT #3: nam='Disk file operations I/O' ela= 113 FileOperation=2 fileno=1 filetype=1 obj#=-1 tim=1446296773013153
WAIT #3: nam='control file sequential read' ela= 44 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296773013223
WAIT #3: nam='control file sequential read' ela= 69 file#=1 block#=1 blocks=1 obj#=-1 tim=1446296773039515
WAIT #3: nam='control file sequential read' ela= 144975 file#=0 block#=3 blocks=8 obj#=-1 tim=1446296773184571
WAIT #3: nam='control file sequential read' ela= 63738 file#=1 block#=3 blocks=8 obj#=-1 tim=1446296773248392

*** 2015-10-31 09:06:17.249
WAIT #3: nam='control file heartbeat' ela= 4000995 p1=0 p2=0 p3=0 obj#=-1 tim=1446296777249544
WAIT #3: nam='control file sequential read' ela= 60 file#=0 block#=3 blocks=8 obj#=-1 tim=1446296777250003
WAIT #3: nam='control file sequential read' ela= 36 file#=1 block#=3 blocks=8 obj#=-1 tim=1446296777250084
WAIT #3: nam='control file sequential read' ela= 7 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777250109
WAIT #3: nam='control file parallel write' ela= 443 files=1 block#=1 requests=1 obj#=-1 tim=1446296777250578
WAIT #3: nam='control file sequential read' ela= 5 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777250612
WAIT #3: nam='control file sequential read' ela= 6 file#=1 block#=1 blocks=1 obj#=-1 tim=1446296777250634
WAIT #3: nam='control file parallel write' ela= 215 files=1 block#=1 requests=1 obj#=-1 tim=1446296777250866
WAIT #3: nam='control file sequential read' ela= 5 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777250905
WAIT #3: nam='control file sequential read' ela= 11096 file#=0 block#=16 blocks=1 obj#=-1 tim=1446296777262041
WAIT #3: nam='control file sequential read' ela= 828 file#=0 block#=18 blocks=1 obj#=-1 tim=1446296777263032
WAIT #3: nam='control file parallel write' ela= 338 files=2 block#=17 requests=2 obj#=-1 tim=1446296777263447
WAIT #3: nam='control file parallel write' ela= 398 files=2 block#=15 requests=2 obj#=-1 tim=1446296777263874
WAIT #3: nam='control file parallel write' ela= 260 files=2 block#=1 requests=2 obj#=-1 tim=1446296777264159
WAIT #3: nam='control file sequential read' ela= 6 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777264181
WAIT #3: nam='control file sequential read' ela= 30 file#=0 block#=3 blocks=8 obj#=-1 tim=1446296777264234
WAIT #3: nam='control file parallel write' ela= 343 files=1 block#=3 requests=1 obj#=-1 tim=1446296777264600
WAIT #3: nam='control file sequential read' ela= 31 file#=0 block#=3 blocks=1 obj#=-1 tim=1446296777264743
WAIT #3: nam='control file parallel write' ela= 161 files=1 block#=4 requests=1 obj#=-1 tim=1446296777265035
WAIT #3: nam='control file sequential read' ela= 5 file#=0 block#=4 blocks=1 obj#=-1 tim=1446296777265058
WAIT #3: nam='control file parallel write' ela= 146 files=1 block#=5 requests=1 obj#=-1 tim=1446296777265219
WAIT #3: nam='control file sequential read' ela= 7 file#=0 block#=5 blocks=1 obj#=-1 tim=1446296777265248
WAIT #3: nam='control file parallel write' ela= 211 files=1 block#=6 requests=1 obj#=-1 tim=1446296777265475
WAIT #3: nam='control file sequential read' ela= 134 file#=0 block#=6 blocks=1 obj#=-1 tim=1446296777265625
WAIT #3: nam='control file parallel write' ela= 8503 files=1 block#=7 requests=1 obj#=-1 tim=1446296777274158
WAIT #3: nam='control file sequential read' ela= 9 file#=0 block#=7 blocks=1 obj#=-1 tim=1446296777274229
WAIT #3: nam='control file parallel write' ela= 197 files=1 block#=8 requests=1 obj#=-1 tim=1446296777274449
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=8 blocks=1 obj#=-1 tim=1446296777274467
WAIT #3: nam='control file parallel write' ela= 129 files=1 block#=9 requests=1 obj#=-1 tim=1446296777274607
WAIT #3: nam='control file sequential read' ela= 3 file#=0 block#=9 blocks=1 obj#=-1 tim=1446296777274624
WAIT #3: nam='control file parallel write' ela= 277 files=1 block#=10 requests=1 obj#=-1 tim=1446296777274912
WAIT #3: nam='control file sequential read' ela= 347 file#=0 block#=10 blocks=1 obj#=-1 tim=1446296777275274
WAIT #3: nam='control file parallel write' ela= 403 files=1 block#=11 requests=1 obj#=-1 tim=1446296777275717
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=11 blocks=1 obj#=-1 tim=1446296777275736
WAIT #3: nam='control file parallel write' ela= 130 files=1 block#=12 requests=1 obj#=-1 tim=1446296777275877
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=12 blocks=1 obj#=-1 tim=1446296777275894
WAIT #3: nam='control file parallel write' ela= 106 files=1 block#=13 requests=1 obj#=-1 tim=1446296777276010
WAIT #3: nam='control file sequential read' ela= 3 file#=0 block#=13 blocks=1 obj#=-1 tim=1446296777276026
WAIT #3: nam='control file sequential read' ela= 63871 file#=0 block#=282 blocks=1 obj#=-1 tim=1446296777339913
WAIT #3: nam='control file parallel write' ela= 8327 files=2 block#=281 requests=2 obj#=-1 tim=1446296777348493
WAIT #3: nam='control file parallel write' ela= 340 files=2 block#=18 requests=2 obj#=-1 tim=1446296777348897
WAIT #3: nam='control file parallel write' ela= 293 files=2 block#=16 requests=2 obj#=-1 tim=1446296777349217
WAIT #3: nam='control file parallel write' ela= 289 files=2 block#=1 requests=2 obj#=-1 tim=1446296777349531
WAIT #3: nam='control file sequential read' ela= 7 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777349554
WAIT #3: nam='control file sequential read' ela= 77 file#=0 block#=23 blocks=1 obj#=-1 tim=1446296777365937
WAIT #3: nam='control file sequential read' ela= 12930 file#=0 block#=181 blocks=1 obj#=-1 tim=1446296777378929
WAIT #3: nam='control file sequential read' ela= 19939 file#=0 block#=309 blocks=1 obj#=-1 tim=1446296777422063
WAIT #3: nam='control file sequential read' ela= 18 file#=0 block#=281 blocks=1 obj#=-1 tim=1446296777446057
WAIT #3: nam='control file parallel write' ela= 341 files=2 block#=310 requests=2 obj#=-1 tim=1446296777446470
WAIT #3: nam='control file sequential read' ela= 520 file#=0 block#=283 blocks=1 obj#=-1 tim=1446296777447014
WAIT #3: nam='control file sequential read' ela= 11495 file#=0 block#=519 blocks=1 obj#=-1 tim=1446296777459545
WAIT #3: nam='control file sequential read' ela= 17 file#=0 block#=281 blocks=1 obj#=-1 tim=1446296777459856
WAIT #3: nam='control file parallel write' ela= 12696 files=2 block#=520 requests=2 obj#=-1 tim=1446296777472579
WAIT #3: nam='control file parallel write' ela= 293 files=2 block#=17 requests=2 obj#=-1 tim=1446296777473101
WAIT #3: nam='control file parallel write' ela= 336 files=2 block#=15 requests=2 obj#=-1 tim=1446296777473462
WAIT #3: nam='control file parallel write' ela= 416 files=2 block#=1 requests=2 obj#=-1 tim=1446296777473902
WAIT #3: nam='control file sequential read' ela= 7 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777473929
WAIT #3: nam='rdbms ipc reply' ela= 700 from_process=10 timeout=910 p3=0 obj#=-1 tim=1446296777492487
WAIT #3: nam='rdbms ipc reply' ela= 8099 from_process=11 timeout=1800 p3=0 obj#=-1 tim=1446296777501110
WAIT #3: nam='control file sequential read' ela= 6 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777501170
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=16 blocks=1 obj#=-1 tim=1446296777501191
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=18 blocks=1 obj#=-1 tim=1446296777501206
WAIT #3: nam='rdbms ipc reply' ela= 521 from_process=12 timeout=2147483647 p3=0 obj#=-1 tim=1446296777501843
WAIT #3: nam='control file sequential read' ela= 6 file#=0 block#=1 blocks=1 obj#=-1 tim=1446296777502027
WAIT #3: nam='control file sequential read' ela= 5 file#=1 block#=1 blocks=1 obj#=-1 tim=1446296777502047
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=16 blocks=1 obj#=-1 tim=1446296777502062
WAIT #3: nam='control file sequential read' ela= 4 file#=0 block#=18 blocks=1 obj#=-1 tim=1446296777502076
WAIT #3: nam='control file sequential read' ela= 6 file#=0 block#=281 blocks=1 obj#=-1 tim=1446296777502096
WAIT #3: nam='ADR block file read' ela= 37247 =0 =0 =0 obj#=-1 tim=1446296777675074
WAIT #3: nam='ADR block file read' ela= 7722 =0 =0 =0 obj#=-1 tim=1446296777683459
WAIT #3: nam='ADR block file read' ela= 25901 =0 =0 =0 obj#=-1 tim=1446296777709757
WAIT #3: nam='ADR block file read' ela= 1663 =0 =0 =0 obj#=-1 tim=1446296777711874
WAIT #3: nam='ADR block file read' ela= 35072 =0 =0 =0 obj#=-1 tim=1446296777747572
WAIT #3: nam='ADR block file read' ela= 14872 =0 =0 =0 obj#=-1 tim=1446296777762855
WAIT #3: nam='ADR block file read' ela= 17409 =0 =0 =0 obj#=-1 tim=1446296777780799
WAIT #3: nam='ADR block file read' ela= 29847 =0 =0 =0 obj#=-1 tim=1446296777850437
WAIT #3: nam='ADR block file read' ela= 13570 =0 =0 =0 obj#=-1 tim=1446296777864497
WAIT #3: nam='ADR block file read' ela= 20071 =0 =0 =0 obj#=-1 tim=1446296777885196
WAIT #3: nam='ADR block file read' ela= 880 =0 =0 =0 obj#=-1 tim=1446296777886715

*** 2015-10-31 09:06:17.944
WAIT #3: nam='ADR block file read' ela= 27761 =0 =0 =0 obj#=-1 tim=1446296777944148
WAIT #3: nam='ADR block file read' ela= 10647 =0 =0 =0 obj#=-1 tim=1446296777982848
WAIT #3: nam='ADR block file read' ela= 14849 =0 =0 =0 obj#=-1 tim=1446296777998699
WAIT #3: nam='ADR block file read' ela= 35131 =0 =0 =0 obj#=-1 tim=1446296778034599
WAIT #3: nam='ADR block file read' ela= 14513 =0 =0 =0 obj#=-1 tim=1446296778050044
WAIT #3: nam='ADR block file read' ela= 1261 =0 =0 =0 obj#=-1 tim=1446296778063093
WAIT #3: nam='ADR block file read' ela= 23532 =0 =0 =0 obj#=-1 tim=1446296778105361
WAIT #3: nam='ADR block file read' ela= 15768 =0 =0 =0 obj#=-1 tim=1446296778121825
WAIT #3: nam='ADR block file read' ela= 929 =0 =0 =0 obj#=-1 tim=1446296778123475
WAIT #3: nam='ADR block file read' ela= 490 =0 =0 =0 obj#=-1 tim=1446296778124444
WAIT #3: nam='ADR block file read' ela= 752 =0 =0 =0 obj#=-1 tim=1446296778126288
WAIT #3: nam='ADR block file read' ela= 454 =0 =0 =0 obj#=-1 tim=1446296778127213
WAIT #3: nam='ADR block file read' ela= 646 =0 =0 =0 obj#=-1 tim=1446296778128271
WAIT #3: nam='ADR block file read' ela= 231 =0 =0 =0 obj#=-1 tim=1446296778128965
WAIT #3: nam='ADR block file read' ela= 1045 =0 =0 =0 obj#=-1 tim=1446296778130391
WAIT #3: nam='ADR block file read' ela= 593 =0 =0 =0 obj#=-1 tim=1446296778131413
WAIT #3: nam='ADR block file read' ela= 391 =0 =0 =0 obj#=-1 tim=1446296778132208
WAIT #3: nam='ADR block file read' ela= 15954 =0 =0 =0 obj#=-1 tim=1446296778163400
WAIT #3: nam='ADR block file read' ela= 1006 =0 =0 =0 obj#=-1 tim=1446296778165076
WAIT #3: nam='ADR block file read' ela= 767 =0 =0 =0 obj#=-1 tim=1446296778166364
WAIT #3: nam='ADR block file read' ela= 227 =0 =0 =0 obj#=-1 tim=1446296778168120
WAIT #3: nam='ADR block file read' ela= 392 =0 =0 =0 obj#=-1 tim=1446296778168904
WAIT #3: nam='ADR block file read' ela= 702 =0 =0 =0 obj#=-1 tim=1446296778185168
WAIT #3: nam='ADR block file read' ela= 15825 =0 =0 =0 obj#=-1 tim=1446296778201438
WAIT #3: nam='ADR block file read' ela= 4704 =0 =0 =0 obj#=-1 tim=1446296778206743
WAIT #3: nam='ADR block file read' ela= 14386 =0 =0 =0 obj#=-1 tim=1446296778244721
WAIT #3: nam='ADR block file read' ela= 1116 =0 =0 =0 obj#=-1 tim=1446296778247177
WAIT #3: nam='ADR block file read' ela= 575 =0 =0 =0 obj#=-1 tim=1446296778265971
WAIT #3: nam='ADR block file read' ela= 523 =0 =0 =0 obj#=-1 tim=1446296778266884

10,要分析TRACE文件的内容，先要理解下上述几个等待事件各个参数的含义

rdbms ipc reply

Disk file operations I/O

control file sequential read

control file heartbeat

control file parallel write

ADR block file read

我们依次来看
SQL> select name,parameter1,parameter2,parameter3 from v$event_name where name='rdbms ipc reply';

NAME PARAMETER1 PARAMETER2 PARAMETER3
------------------------------ ------------------------------ ------------------------------ ------------------------------
rdbms ipc reply from_process timeout

SQL> select addr,pid,spid,pname from v$process where pid in (10,11,12);

ADDR PID SPID PNAME
---------------- ---------- ------------------------------------------------ ----------
00000000DD5A7E40 10 8281 DBW0
00000000DD5A8E80 11 8283 LGWR
00000000DD5A9EC0 12 8285 CKPT

我们把与rdbms ipc reply相关的等待事件记录摘录出来，

WAIT #3: nam='rdbms ipc reply' ela= 61923 from_process=10 timeout=60 p3=0 obj#=-1 tim=1446296772825546

WAIT #3: nam='rdbms ipc reply' ela= 118283 from_process=12 timeout=900 p3=0 obj#=-1 tim=1446296772983943

WAIT #3: nam='rdbms ipc reply' ela= 700 from_process=10 timeout=910 p3=0 obj#=-1 tim=1446296777492487
WAIT #3: nam='rdbms ipc reply' ela= 8099 from_process=11 timeout=1800 p3=0 obj#=-1 tim=1446296777501110

WAIT #3: nam='rdbms ipc reply' ela= 521 from_process=12 timeout=2147483647 p3=0 obj#=-1 tim=1446296777501843

由上可见，从nomount到mount,依次是dbwr,ckpt,dbwr,lgwr,ckpt几个后台进程参考了从nomount至mount的工作，
也就是如果这些后台进程出现故障，数据库无法从nomount到mount状态

然后再来看等待事件Disk file operations I/O

SQL> select name,parameter1,parameter2,parameter3 from v$event_name where name='Disk file operations I/O';

NAME PARAMETER1 PARAMETER2 PARAMETER3
------------------------------ ------------------------------ ------------------------------ ------------------------------
Disk file operations I/O FileOperation fileno filetype

摘录下与此等待事件相关的TRACE文件内容
WAIT #3: nam='Disk file operations I/O' ela= 138 FileOperation=2 fileno=0 filetype=1 obj#=-1 tim=1446296772993312
WAIT #3: nam='Disk file operations I/O' ela= 113 FileOperation=2 fileno=1 filetype=1 obj#=-1 tim=1446296773013153
从上面fileno的值来看，有0和1，这对应哪些文件呢？当然还有fileoperation=2，又是什么含义呢？obj#=-1对应哪个对象呢？下面我们来分析下。

SQL> select file#,name from v$datafile;

FILE# NAME
---------- ------------------------------------------------------------
1 /oracle/oradata/guowang/system01.dbf
2 /oracle/oradata/guowang/sysaux01.dbf
3 /oracle/oradata/guowang/uniform1.dbf
4 /oracle/oradata/guowang/users01.dbf
5 /oracle/oradata/guowang/new_undo1.dbf
6 /oracle/oradata/guowang/t_err1.dbf
7 /oracle/oradata/guowang/tbs_undo_nb.dbf
8 /oracle/oradata/guowang/new_add1.dbf

8 rows selected.

SQL> select name,file_size_blks,block_size from v$controlfile;

NAME FILE_SIZE_BLKS BLOCK_SIZE
------------------------------------------------------------ -------------- ----------
/oracle/oradata/guowang/control01.ctl 666 16384
/oracle/oradata/guowang/control02.ctl 666 16384

可见每个控制文件的数据块大小为16K
SQL> select 16384/1024 from dual;

16384/1024
----------
16

大家注意观察，TRACE里面等待事件涉及的对象全是obj#=-1,我推测是如下的8.0.0.0.0,从这里可以看出来，nomount到mount只是用到了bootstrap$中存储对象的obj#=-1的对象而已，其后的对象没有用到
SQL> select line#,obj#,sql_text from bootstrap$ where obj# in (-1,0);

LINE# OBJ# SQL_TEXT
---------- ---------- ----------------------------------------------------------------------------------------------------
-1 -1 8.0.0.0.0
0 0 CREATE ROLLBACK SEGMENT SYSTEM STORAGE ( INITIAL 112K NEXT 56K MINEXTENTS 1 MAXEXTENTS 32765 OBJNO
0 EXTENTS (FILE 1 BLOCK 128))