Re: Big checkpoints

In article <9anulb$rls$1_at_news.netmar.com>, <fish9969_at_supanet.com> writes:
>
>Hi,
>I've go a small db of about 2Gb in size and only 40 sessions. The server is
>NT with 3CPU, 2.5Gb
>memory, and RAID5 for data, raid 1 for logs and raid1 for arch logs. The
>version of Oracle is 8.1.6.
>
>The problem I'm getting is that during normal system operation, a log switch
>checkpoint will start,
>and then does not appear to complete for 30 mins! During this time there
>seems to be no undue disk
>activity and the system is not under any real stress. Is there a reason for
>this. SOme params are:
>
>db_block_lru_latches=1
>dbwr_io_slaves=2
>db_block_size = 4096
>log_buffer = 512000
>db_block_buffers = 102400
>
>There are 5 redo groups each with 1 member of 10M (although I'm adding a new
>member per group ASAP).
>
>Any ideas why the check point would take so long? It's driving me mad.
>
>I've set log_checkpoint_time_out to 1800 but this doesn't seem to cause a
>checkpoint (how does this
>work?) I've even tried to set db_file_max_dirty but I'm not sure this is
>doing anything (whats the
>recommendation for this).
>
>Thanks in anticipation
>
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I notice that you have a 400M buffer pool, why? It is probably taking Oracle 30 minutes to scan the buffer pool to find and write all dirty buffers. With only 40 users and 2G of data I doubt that you can efficiently utilize a buffer pool this large. You might want to consider shrinking it. You can check your buffer pool hit ratio after the shrinkage and I doubt that you will notice a significant difference. And why did you set db_block_lru_latches=1 when you have 3 cpu's? I would think you would want at least 1 per cpu at minimum.

• Mark D. Powell --
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