SMON Trace File Reports Messages "SMON: about to recover undo segment X" "SMON: mark undo segment X as available" (Doc ID 821743.1)

Symptoms

-- Problem Statement:

The following messages continue to be written to an SMON trace file:
..
*** SERVICE NAME:() 2009-05-04 17:26:59.173
*** SESSION ID:(438.1) 2009-05-04 17:26:59.173
SMON: about to recover undo segment 34
SMON: mark undo segment 34 as available
SMON: about to recover undo segment 83
SMON: mark undo segment 83 as available
SMON: about to recover undo segment 113
SMON: mark undo segment 113 as available

The messages are always pointing to the same three undo segments, in this case undo segments 34, 83 and 113.

Changes

In this case, the database was being switched from using manual rollback segments to Automatic Undo Management (AUM). The database was shutdown, AUM was enabled, and the database restarted.

Cause

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