Oracle Wait Interface: A Practical Guide to Performance Diagnostics & Tuning (Osborne ORACLE Press Series)

File header dumps will be very useful while diagnosing errors related to media recovery. These file headers will contain the various SCN numbers used for database recovery operations and hold important information such as checkpoint details, the redo information address (rba), extent information, and the high water mark for that datafile.

Syntax

The following methods show how to dump the file header information.

Using ALTER SESSION

In the following ALTER SESSION command, the file headers are dumped at level 10.

alter session set events 'immediate trace name file_hdrs level 10'

Using oradebug

The following oradebug command sequence shows how to dump file headers at level 10.

oradebug setmypid oradebug unlimit oradebug dump file_hdrs 10

Controlling the Dump Information Using Levels

The file headers dump is taken between levels 1 and 10. The following output is taken from a dump of file headers at level 10.

DATA FILE #1: (name #4) D:\ORACLE\PRODUCT.1.0\DB_1\GOPAL\SYSTEM01.DBF creation size=38400 block size=8192 status=0xe head=4 tail=4 dup=1 tablespace 0, index=1 krfil=1 prev_file=0 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00 Checkpoint cnt:75 scn: 0x0000.000438f4 04/01/2004 00:53:01 Stop scn: 0xffff.ffffffff 03/31/2004 20:21:22 Creation Checkpointed at scn: 0x0000.00000009 03/22/2004 16:46:41 thread:1 rba:(0x1.3.10) enabled threads: 01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 Offline scn: 0x0000.00000000 prev_range: 0 Online Checkpointed at scn: 0x0000.00000000 thread:0 rba:(0x0.0.0) enabled threads: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 Hot Backup end marker scn: 0x0000.00000000 aux_file is NOT DEFINED V10 STYLE FILE HEADER: Compatibility Vsn = 168821248=0xa100200 Db ID=580029651=0x22928cd3, Db Name='GOPAL' Activation ID=0=0x0 Control Seq=252=0xfc, File size=38400=0x9600 File Number=1, Blksiz=8192, File Type=3 DATA Tablespace #0 - SYSTEM rel_fn:1 Creation at scn: 0x0000.00000009 03/22/2004 16:46:41 Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0 reset logs count:0x1f153853 scn: 0x0000.00000001 reset logs terminal rcv data:0x0 scn: 0x0000.00000000 prev reset logs count:0x0 scn: 0x0000.00000000 prev reset logs terminal rcv data:0x0 scn: 0x0000.00000000 recovered at 04/01/2004 00:52:53 status:0x2004 root dba:0x00400179 chkpt cnt: 75 ctl cnt:74 begin-hot-backup file size: 0 Checkpointed at scn: 0x0000.000438f4 04/01/2004 00:53:01 thread:1 rba:(0x35.2.10) 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 Platform Information: Creation Platform ID: 7 Current Platform ID: 7 Last Platform ID: 7