Export (exp) taking long time and reading UNDO

Question

Hi Guys,
Oracle 9.2.0.7 on AIX 5.3
A schema level export job is scheduled at night. Since day before yesterday it has been taking really long time. It used to finish in 8 hours or so but yesterday it took around 20 hours and was still running. The schema size to be exported is around 1 TB. (I know it is bit stupid to take such daily exports but customer requirement, you know ;) ) Today again it is still running although i scheduled it to run even earlier by 1 and 1/2 hour.
The command used is:
exp userid=abc/abc file=expabc.pipe buffer=100000 rows=y direct=y
recordlength=65535 indexes=n triggers=n grants=y
constraints=y statistics=none log=expabc.log owner=abcI have monitored the session and all the time the wait event is db file sequential read. From p1 i figured out that all the datafiles it reads belong to UNDO tablespace. What surprises me is that when consistent=Y is not specified should it go to read UNDO so frequently ?
There is total of around 1800 tables in the schema; what i can see from the export log is that it exported around 60 tables and has been stuck since then. The logfile, dumpfile both has not been updated since long time.
Any hints, clues in which direction to diagnose please.
Any other information required, please let me know.
Regards,
Amardeep Sidhu

Answer 1

Thanks Hemant.
As i wrote above, it runs from a cron job.
Here is the output from a simple SQL querying v$session_wait & v$datafile:
13:50:00 SQL> l
  1* select a.sid,a.p1,a.p2,a.p3,b.file#,b.name
  from v$session_wait a,v$datafile b where a.p1=b.file# and a.sid=154
13:50:01 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        509     158244          1        509 /<some_path_here>/undotbs_45.dbf
13:50:03 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        509     157566          1        509 /<some_path_here>/undotbs_45.dbf
13:50:07 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        509     157016          1        509 /<some_path_here>/undotbs_45.dbf
13:50:11 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        509     156269          1        509 /<some_path_here>/undotbs_45.dbf
13:50:16 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        508     167362          1        508 /<some_path_here>/undotbs_44.dbf
13:50:58 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        508     166816          1        508 /<some_path_here>/undotbs_44.dbf
13:51:02 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        508     165024          1        508 /<some_path_here>/undotbs_44.dbf
13:51:14 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        507     159019          1        507 /<some_path_here>/undotbs_43.dbf
13:52:09 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        506     193598          1        506 /<some_path_here>/undotbs_42.dbf
13:52:12 SQL> /
       SID         P1         P2         P3      FILE# NAME
       154        506     193178          1        506 /<some_path_here>/undotbs_42.dbf
13:52:14 SQL>Regards,
Amardeep Sidhu
Edited by: Amardeep Sidhu on Jun 9, 2010 2:26 PM
Replaced few paths with <some_path_here> ;)