結論

1，oracle 11g bbed不支援直接用map檢視undo header block
2, 得出上述結論有幾個原因：
   A,BBED MAP報錯
   B,我MAP了UNDO HEADER BLOCK的前後相領塊，即可以MAP

測試   

SQL> select * from v$version where rownum=1;


BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production




SQL> select segment_name,header_file,header_block from dba_segments where segment_name=(select name from v$rollname where usn=156);


SEGMENT_NAME                                       HEADER_FILE HEADER_BLOCK
-------------------------------------------------- ----------- ------------
_SYSSMU156_1055097348$                                       7          144


BBED> map /v
 File: /oracle/oradata/guowang/tbs_undo_nb.dbf (7)
 Block: 144                                   Dba:0x01c00090
------------------------------------------------------------
BBED-00400: invalid blocktype (38)




BBED> dump /v
 File: /oracle/oradata/guowang/tbs_undo_nb.dbf (7)
 Block: 144     Offsets:    0 to  511  Dba:0x01c00090
-------------------------------------------------------
 26a20000 9000c001 4d2f6802 00000204 l &.......M/h.....
 99bb0000 00000000 00000000 00000000 l ................
 00000000 02000000 0f000000 f00f0000 l ................
 00000000 04000000 07000000 9500c001 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 02000000 l ................
 00000000 00000000 00000040 9100c001 l ...........@....
 07000000 7801c001 08000000 00000000 l ....x...........
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................
 00000000 00000000 00000000 00000000 l ................


 <16 bytes per line>


 BBED> set file 7 block 143
        FILE#           7
        BLOCK#          143


BBED> map
 File: /oracle/oradata/guowang/tbs_undo_nb.dbf (7)
 Block: 143                                   Dba:0x01c0008f
------------------------------------------------------------
 Undo Data


 struct kcbh, 20 bytes                      @0       


 struct ktubh, 20 bytes                     @20      


 ub1 freespace[5040]                        @40      


 ub1 undodata[3108]                         @5080    


 ub4 tailchk                                @8188    




BBED> set file 7 block 145
        FILE#           7
        BLOCK#          145


BBED> map
 File: /oracle/oradata/guowang/tbs_undo_nb.dbf (7)
 Block: 145                                   Dba:0x01c00091
------------------------------------------------------------
 Undo Data


 struct kcbh, 20 bytes                      @0       


 struct ktubh, 140 bytes                    @20      


 ub1 freespace[252]                         @160     


 ub1 undodata[7776]                         @412     


 ub4 tailchk                                @8188    


BBED> 

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