hi

oracle needs the full image of the database
from the export's start to end.
if the data block has been changed after your export
has started it goes to rollback segment to get the
previous image.
if it fails to get for any of the block you get this error.


droping and recreating "rb5" alone will not solve the problem.

you will have to create all the rollback segments with high
minextents.(this is the oracle recommentation)

if yours is a transaction intensive then:

you can try adding more rollback segments.

you can set transactions_per_rollback_segment to high.

how much time your export takes to complete.

what is number of transactions that can execute
during the exporting period.

your
(count of rollback segments) * transactions_per_rollback_segment
should be greater than the number of transactions executed
during that exporting period.


-Raja