Today I got a message in the alert log which is new to me:
Fri Jun 13 00:00:24 2014 Thread 1 cannot allocate new log, sequence 514 Private strand flush not complete
Private strand flush not complete… sounds similar to checkpoint not complete. So the next step brought me to Metalink and there I found note 372557.1.
There is always shared strands and a number of private strands .
Oracle 10g has some major changes in the mechanisms for redo (and undo), which seem to be aimed at reducing contention.
Instead of redo being recorded in real time, it can be recorded 'privately' and pumped into the redo log buffer on commit.
Similarly the undo can be generated as 'in memory undo' and applied in bulk. This affect the memory used for redo management and the possibility to flush it in pieces. The message you get is related to internal Cache Redo File management.
NOTE: You can disregard these messages as normal messages.