file_hdrs信息的来源

SQL> conn / as sysdba;
已连接到空闲例程。
SQL> startup mount
ORACLE 例程已经启动。

Total System Global Area  118562308 bytes
Fixed Size                   454148 bytes
Variable Size              75497472 bytes
Database Buffers           41943040 bytes
Redo Buffers                 667648 bytes
数据库装载完毕。
SQL> alter session set events 'immediate trace name file_hdrs  level 10';

会话已更改。

 我们可以到udump目录下，打开查看其中的信息，截取USERS表空间中的控制文件，以FILE HEADER:为分界线，之前的信息都来自于控制文件。
DATA FILE #5:
  (name #5) D:\ORACLE\ORADATA\ICMNLSDB\USERS01.DBF
creation size=0 block size=8192 status=0xe head=5 tail=5 dup=1
 tablespace 5, index=5 krfil=5 prev_file=0
 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00
 Checkpoint cnt:443 scn: 0x0000.0037adb2 12/25/2007 13:07:27
 Stop scn: 0x0000.0037adb2 12/25/2007 13:07:27
 Creation Checkpointed at scn:  0x0000.0000163e 07/23/2007 18:11:23
 thread:0 rba:(0x0.0.0)
 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000
  00000000 00000000
 Offline scn: 0x0000.002f3762 prev_range: 0
 Online Checkpointed at scn:  0x0000.00374c52 12/24/2007 16:24:06
 thread:1 rba:(0x1.1a16f.10)
 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000
  00000000 00000000
 Hot Backup end marker scn: 0x0000.00000000
 aux_file is NOT DEFINED
 FILE HEADER:
 Software vsn=153092096=0x9200000, Compatibility Vsn=134217728=0x8000000
 Db ID=862305779=0x3365bdf3, Db Name='ICMNLSDB'
 Activation ID=0=0x0
 Control Seq=1264=0x4f0, File size=3200=0xc80
 File Number=5, Blksiz=8192, File Type=3 DATA
Tablespace #5 - USERS  rel_fn:5
Creation   at   scn: 0x0000.0000163e 07/23/2007 18:11:23
Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0
 reset logs count:0x2643577e scn: 0x0000.0033c202 recovered at 12/14/2007 16:38:10
 status:0x0 root dba:0x00000000 chkpt cnt: 443 ctl cnt:442
begin-hot-backup file size: 0
Checkpointed at scn:  0x0000.0037adb2 12/25/2007 13:07:27
 thread:1 rba:(0x1.1a640.10)
 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000
  00000000 00000000
Backup Checkpointed at scn:  0x0000.00000000
 thread:0 rba:(0x0.0.0)
 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000
  00000000 00000000
External cache id: 0x0 0x0 0x0 0x0
Absolute fuzzy scn: 0x0000.00000000
Recovery fuzzy scn: 0x0000.00000000 01/01/1988 00:00:00
Terminal Recovery Stamp scn: 0x0000.00000000 01/01/1988 00:00:00
 
现在我们将数据文件 D:\ORACLE\ORADATA\ICMNLSDB\USERS01.DBF 改名，此时重新转存一下，看一下trace文件的内容，来判断结果
DATA FILE #5:
  (name #5) D:\ORACLE\ORADATA\ICMNLSDB\USERS01.DBF
creation size=0 block size=8192 status=0xe head=5 tail=5 dup=1
 tablespace 5, index=5 krfil=5 prev_file=0
 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00
 Checkpoint cnt:443 scn: 0x0000.0037adb2 12/25/2007 13:07:27
 Stop scn: 0x0000.0037adb2 12/25/2007 13:07:27
 Creation Checkpointed at scn:  0x0000.0000163e 07/23/2007 18:11:23
 thread:0 rba:(0x0.0.0)
 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000
  00000000 00000000
 Offline scn: 0x0000.002f3762 prev_range: 0
 Online Checkpointed at scn:  0x0000.00374c52 12/24/2007 16:24:06
 thread:1 rba:(0x1.1a16f.10)
 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000
  00000000 00000000
 Hot Backup end marker scn: 0x0000.00000000
 aux_file is NOT DEFINED
ORA-01157: 无法标识/锁定数据文件 5 - 请参阅 DBWR 跟踪文件
ORA-01110: 数据文件 5: 'D:\ORACLE\ORADATA\ICMNLSDB\USERS01.DBF'
*** Error 1157 in open/read file # 5 ***

所以我们可以判断FILE HEADER:的信息是来自于各个数据文件！