Can Undo Tablespace share across multiple DB nodes?

[Hari]

Dear Erman,

We have a 5 Node RAC Database for one of my Production Instance. Today we have faced an issue for Undo Tablespace.

There was Concurrent Programs which were running on DB node 1 which has failed with ORA-01555 Snapshot too old error.

The program was running on node 1 had used Undo Segment which belongs to node 5 undo tablespace which has almost 100% used.

my questions are
1. Can Undo Tablespace share across multiple node?
2. If yes, how can we share it? If the answer is No, How it happened today in my environment? Is there logic to access different db node undo segment?

CONCURRENT_QUEUE_NAME     USER_CONCURRENT_QUEUE_NAME                         PROCESS_COUNT NODE_NAME       DB_INSTANCE

------------------------- -------------------------------------------------- ------------- --------------- ----------------

SALES                   SALES                                                   50 hostname       inst_1

SQL> select instance_num,TABLESPACE_NAME, SEGMENT_NAME from dba_rollback_segs where SEGMENT_NAME='_SYSSMU2604_3127774908$';

INSTANCE_NUM                             TABLESPACE_NAME                SEGMENT_NAME
---------------------------------------- ------------------------------ ------------------------------
5                                        APPS_UNDOTS5                   _SYSSMU2604_3127774908$



Thanks In Advance.

Thanks,
Hari.

[Hari]

Dear Erman,

Could you reply on this when you get time?


Thanks,
Hari

[ErmanArslansOracleBlog]

1)No, you can't have shared undo in RAC.
shared undo is concept used in multitenant environments.
But still for RAC, there is one active undo tablespace for each instance.

In multitenant environments, shared undo mode means that there is one active undo tablespace for a single-instance CDB.

2)Probably, the records your session(node node1) was querying , were updated earlier in node5.. and that's why oracle put the old version of those records in undo tablespace of node5.. That's why, your query on node1, tried to reach the undo of node5.

[Hari]

Dear Erman,

Thanks a lot for clarification..

Thanks,
Hari