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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
-Nikee
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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.
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.
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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
-Nikee
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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.
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.
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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
-Nikee
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have you read any of the answers?
your undo_retention is messed up, nothing to do with tablespace size!!
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