Re: CHECKPOINTS QUESTION

Alexander Bardos wrote:
>
> 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.
>
> --
> ------
> Alex Bardos <alexbrds_at_unix.infoserve.net>
> ------

Checkpoint does a flush of all dirty blocks but there are also other mechanisms at work. Oracle writes dirty blocks to disk on a timed basis. An asynch write is also scheduled if the LRU chain get too long. You should never come close to actually running out of blocks. Received on Tue Oct 08 1996 - 00:00:00 CEST