My Oracle Version:11.2.0.1.0 64bit on windows 8 -64bit.This is not a high transaction database.my UNDOTB size is 4GB and retention is 15m.
When I am exporting full database using typical exp, I get the following error.
Snapshot Too Old Error detected: SQL ID 18rf6d6zdsny8, Snapshot SCN 0x0000.b3652a9d, Recent SCN 0x0000.b368a1cf, Undo Tablespace UNDOTBS1, Current Undo Retention 1111. I checked the SQL#18rf6d6zdsny8 is as follows.

SELECT OBJID, DOBJID, OWNER, OWNERID, NAME, TBLSPACE, SIZE$, TSNO, FILENO, BLOCKNO, PCTFREE$, PCTUSED$, INITRANS, MAXTRANS, HASHKEYS, FUNCTION, AVGCHN, DEGREE, INSTANCES, CACHE, FUNCTXT, FUNCLEN, SINGLE_TABLE, TFLAGS
FROM SYS.EXU8CLU
WHERE OWNERID != 0 ORDER BY OWNERID
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When I checked,there was a blocking session from exp util.I killed that session. Shutdown immediate was not working. Then I tried shutdown abort. and restart the database.After that the exp utility was working fine.Masters, Could you please help me?