Troubleshooting ORA-01555/ORA-01628/ORA-30036 During Export and Import (Doc ID 1579437.1)

Troubleshooting ORA-01555/ORA-01628/ORA-30036 During Export and Import (Doc ID 1579437.1)

APPLIES TO:

Oracle Database - Enterprise Edition - Version 9.2.0.1 to 11.2.0.4 [Release 9.2 to 11.2]
Information in this document applies to any platform.

PURPOSE

Purpose of this document is to have a checklist for troubleshooting ORA-01555/ORA-01628/ORA-30036 during export and import. 

This document is intended to provide a checklist for ORA-01555 / ORA-01628 / ORA-30036 Troubleshooting during export and import

This note will also discuss some known issues on this subject.

This note also discusses some of the known issues related to this topic

TROUBLESHOOTING STEPS

Before diagnosing undo errors reported during export and import, it is important first to check UNDO tablespace utilization and tuned undo retention as follow :

Before the diagnosis of the reporting period the export and import of undo mistakes, it is important to first check UNDO table space utilization and tuned undo retention, as shown below

SQL> SELECT DISTINCT STATUS,TABLESPACE_NAME, SUM(BYTES), COUNT(*) FROM DBA_UNDO_EXTENTS GROUP BY STATUS, TABLESPACE_NAME;

SQL> select max(maxquerylen),max(tuned_undoretention) from v$undostat;

SQL> select max(maxquerylen),max(tuned_undoretention) from DBA_HIST_UNDOSTAT;

SQL> select sum(bytes) from dba_free_space where tablespace_name='&UNDOTBS';

Before proceed, Invistiagte/Resolve any excessive allocation of ACTIVE/UNEXPIRED extents and high calculation of tuned_undoretention.

Before continuing, please check / solve a lot of computing any over-allocation ACTIVE / UNEXPIRED extents and the tuned_undoretention

1) ORA-01555 during export   During export to ORA-01555

check alert log and export log to determine 1555 error message. We have two different types of 1555 error :

Check the alert log and export log to determine the 1555 error message. We have two different types of error 1555

Accessing UNDO ORA-1555 A Data AT LOB segment:.   ORA-1555 LOB segment data access UNDO

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

notice that segment name is null "".

or/and

ORA-22924: snapshot too old

Accessing UNDO ORA-1555 B AT UNDO TABLESPACE Data:.   ORA-1555 to access data in the UNDO UNDO tablespace

ORA-01555: snapshot too old: rollback segment number 107 with name "_SYSSMU107_1253191395$" too small

notice that segment name is existing "_SYSSMU107_1253191395$" which mean undo data inside UNDO tablespace.

Please note that the name of the existing segment of "_SYSSMU107_1253191395 $", which means that the data in the UNDO undo table space.

a. ORA-1555 accessing UNDO data at LOB segment :

ORA-01555 for LOB segment is caused by one of the following reasons :

ORA-01555 LOB segment is one of the following causes

Corruption the LOB segment 1.:   the LOB damaged segment

To check the LOB table corruption, review  the following documents: To check LOB table is damaged, please review the following documents

Export Receives The Errors ORA-1555 ORA-22924 ORA-1578 ORA-22922 (Doc ID 787004.1)
Export Fails With ORA-2354 ORA-1555 ORA-22924 and How To Confirm LOB Segment Corruption Using Export Utility? (Doc ID 833635.1)
ORA-01555 And Other Errors while Exporting Table With LOBs, How To Detect Lob Corruption. (Doc ID 452341.1)

2. If no LOB corruption found, so   Issues with Retention / Pctversion values: If no LOB damaged, Retention issues / Pctversion value

You may need to increase Retention / Pctversion   Check following document carefully:. You may need to increase Retention / Pctversion. Double-check the following files

LOBs and ORA-01555 troubleshooting (Doc ID 846079.1)

b. ORA-1555 accessing UNDO data at UNDO tablespace : 

This is handled as a normal 1555 error. You may need to increase undo retention before run export and revert it back after export finish successfully :

This is considered normal 1555 error. You may need to increase undo retention before running the export, the export and after completing successfully restore

alter system set undo_retention=<NEW_VALUE>;

>> run export till finish successfully -. Run the export, until the successful completion of

alter system set undo_retention=<OLD_VALUE>;

Note: It is valid that ORA-1555 reported accessing UNDO data at UNDO tablespace when exporting a table with LOB column. In this case you need to identify which undo segment name is mentioned at 1555 error message as explained above and diagnose accordingly.

Note: When you export a table with LOB columns, ORA-1555 reported data on access to UNDO UNDO table space is valid. In this case, you need to determine which undo segments described above mentioned name in the 1555 error message, and make the appropriate diagnosis

2) ORA-01628 / ORA-  30036 during import during import ORA-01628 / ORA-30036

It is common to encounter 1628 or 30036 error during import. The key point here is the amount of UNDO generated by import utility.

1628 or 30036 typically encountered an error during import. The key is to import UNDO number generated by the program

Generally, to resolve both errors, you need to minimize the undo space allocated during import as much as possible and allocate enough UNDO space.

In general, to solve these two errors, you need to reduce undo space allocated during the import as much as possible, and to allocate sufficient space UNDO

For examples :

- excluding indexes and statistics from import then create/gather them manually after import finish

-  excluding indexes and statistical information from the lead, and then manually create / collect them after the import is complete

- use TABLE_EXISTS_ACTION=REPLACE instead of APPEND or TRUNCATE.

- Instead of using TABLE_EXISTS_ACTION = REPLACE or APPEND TRUNCATE

- use CONTENT=ALL instead of DATA_ONLY

- Use CONTENT = ALL rather than DATA_ONLY

- Make sure all available UNDO segments are ONLINE during the import by setting _rollback_segment_count=999999

- By setting _rollback_segment_count = 999999, the import process to ensure that all of the available segments are in an online state UNDO

SQL> select status,count(*),tablespace_name from dba_rollback_segs group by status,tablespace_name;

Known issues :

Bug 17306264 - ORA-1628: MAX # EXTENTS (32765) REACHED FOR ROLLBACK SEGMENT - OFTEN ENCOUNTERE

Bug 17306264 or the Patch 17306264 for 11g readme contains pre-requisite step to set the below event
event="64000 trace name context forever, level 25"
We recommend to set the event 64000 to level 25, as mentioned in the readme of the patch.

How To Check the Usage of Active Undo Segments in AUM (Doc ID 1337335.1)

Data Pump (or other Oracle process) Reports ORA-01628: Max # Extents (32765) For Rollback Segment _SYSSMUx$ (Doc ID 1434643.1)

ORA-1628 Max # Extents Reached Using AUM On Locally Managed Tablespace (Doc ID 761176.1)

Ora-01628: Max # Extents (32765) Reached For Rollback Segment. (Doc ID 837853.1)

Troubleshooting ORA-30036 - Unable To Extend Undo Tablespace (Doc ID 460481.1) 

Options to decrease use Of UNDO during import (Doc ID 952892.1) 

Error ORA-30036 DataPump Import (IMPDP) Exhausts Undo Tablespace (Doc ID 727894.1) 

Run Out Of Space On Undo Tablespace Using Import/Export DataPump (Doc ID 735366.1)

REFERENCES

NOTE:787004.1 - Export Receives The Errors ORA-1555 ORA-22924 ORA-1578 ORA-22922
NOTE:833635.1 - Export Fails With Errors ORA-2354 ORA-1555 ORA-22924 And How To Confirm LOB Segment Corruption Using Export Utility?
NOTE:452341.1 - ORA-01555 And Other Errors while Exporting Table With LOBs, How To Detect Lob Corruption.
NOTE:846079.1 - LOBs and ORA-01555 troubleshooting
NOTE:1337335.1 - How To Check the Usage of Active Undo Segments in AUM
NOTE:1434643.1 - Data Pump (or other Oracle process) Reports ORA-01628: Max # Extents (32765) For Rollback Segment _SYSSMUx$
NOTE:761176.1 - ORA-1628 Max # Extents Reached Using AUM On Locally Managed Tablespace
NOTE:837853.1 - Ora-01628: Max # Extents (32765) Reached For Rollback Segment.
NOTE:460481.1 - Troubleshooting ORA-30036 - Unable To Extend Undo Tablespace
NOTE:952892.1 - Options to decrease use Of UNDO during import
NOTE:727894.1 - Error ORA-30036 DataPump Import (IMPDP) Exhausts Undo Tablespace
NOTE:735366.1 - Run Out Of Space On UNDO Tablespace Using DataPump Import/Export