Re: Page Cleaners/Idle Writes

Dave, Thanx for the response. I couldn't reach you directly. page cleaners = LRUS is worth trying. I remember seeing your post a couple of weeks ago when we were discussing maximum performance - it was very imformative and it was that reason I was experimenting with Page Cleaners. *Do you understand how an Idle Write is tabulated. Why do I continally see chunk writes when my pages are being flushed outside of checkpoints. thanx Mikea -------- } |> I learn from the admin book that if a page cleaner determines } |> that the buffer pool(MLRU ques) should be flushed it marks a page } |> for flushing, flushes it, } |> rechecks it against the MAX percentage , then keeps working till } |> it reaches the MIN percentage of buffers that can be dirty. } |> To me if a page cleaner is woke up and cleans/flushes pages outside of } |> checkpoints then I would think I should see some idle writes } |> when I use tbstat -F. } |> Yet all my writes continue to be chunk writes. ------- } } Mike Alder writes: } } Mike's issue is cc'ed below. Here is the way to tune to get (for most } circumstances) best performance. Fiirst, ignore the bit in the manual about } tuning page cleaners to disks; tune them == LRUS (8 by default). Set your } LRU_MAX_DIRTY to 10-30, and LRU_MIN_DIRTY to 5-10 below that. Set your } CKPTINTVL to a value that you are comfortable with, given what it will mean } in terms of fast recovery time. If need be, increase your physical log } size. } } The outcome of this is to minimize the amount of time spent doing a checkpoint. } Because all transaction activity stops during checkpoints, you want them to } be as brief as possible. Let the page cleaners keep the queues clean in } the meantime. By having a cleaner per LRU, you stand a better chance of } keeping each queue clean. Because cleaners basically pull a buffer then } block on a write, they tend to accumulate little cpu.