Use consistent =y while exporting & check whether you are getting the error or not.
Export extracts data by issuing a series of SELECT statements and the snapshot
time of each table's data corresponds to when the SELECT statement was issued
for that table. If there is no database activity, then this is not an issue.
However, it is possible to manipulate the table after the export has started
in which case the snapshot of the data may be a factor. Export does not get
an exclusive lock on any table.
There is an option called CONSISTENT=Y. When this is enabled, EXPORT first
issues a SET TRANSACTION READ ONLY command before doing the export. There is a
risk of running out of rollback segment space and getting an "ORA-1555 snapshot
too old (rollback segment too small)" error when doing a long running export.
