CHECKPOINTS QUESTION

Hi,

according to Oracle documentation CHECKPOINTS occur:

• at every log switch
• after LOG_CHECKPOINT_TIMEOUT seconds
• when LOG_CHECKPOINT_INTERVAL number of bytes of redo logs have been written
• at instance shutdown ( normal, immediate )
• forced by DBA ( ALTER ... )
• when TS is taken offline

My question:

What happens when an instance runs out of db buffer cache blocks ( unmodified ) and there are only dirty blocks available? Is this possible at all? Shouldn't the DBWR flush the dirty blocks ( write to OS files / partitions -> do a checkpoint )?
Are the dirty blocks managed on separate lists that are not subjected to the LRU realocation algorithm?

Thanks.

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Alex Bardos	<alexbrds_at_unix.infoserve.net>
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