ORA-01555: snapshot too old: rollback segment number 8 with name "_SYSSMU8$" too smal

Dear Friends,

We are facing the following error, while exporting the Database.

ORA-01555: snapshot too old: rollback segment number 8 with name "_SYSSMU8$" too small

The database is running on 9206 and we are using undo management tablespace. The tablespace size was 12GB prior to the error, and I have increased it to 20GB. The undo retention was 10000 prior to the error and now I have changed it to 900 just to avoid this error while exporting the database.

Is there a way to allocate larger space for these automatic rollback segments example --> "_SYSSMU8$"

Could you please let me know on how to avoid this error.

Thank you,
Nikee

ORA-01555 means Oracle was unable to get a consistent read -decreasing undo_retention should actuallly hurt you.

I would attempt export at a time the database is hit by less I/O activity.

Hello Pablo,

Here are the details on the UNDO tablespace...Can you suggest anything by looking at the following details....

TableSpace Size (kb) Free (kb) Used % Free %
--------------- ------------ ------------ ---------- - -----------
PSAPUNDO 19,455,984 19,050,048 2% 98%

Max. Bytes/Minutes Avg. Bytes/Minutes Max Space (Mb) Avg Space (Mb)
------------------ ------------------ -------------- --------------
40,065,434 1,823,907 573 Mb 26 Mb


Thank you,
Nikee

ORA-01555 means an UNDO entry got overwritten and was not longer available when export utility needed it.

undo_retention should be set to a value at least as large as the expected running time of your transaction -in this case your export session.

undo tablespace should be large enough to cope with the amount of undo generated during whatever value you have set as undo_retention.

My suggestion would be to attempt export again at a time the database is hit by less I/O activity.

Hello Pablo,

What I see is there is enough freespace in the tablespace. Even though we have freespace, do we still see these errors?

Thank you,
Nikee

have you read any of the answers?

your undo_retention is messed up, nothing to do with tablespace size!!