Re: tuning checkpoint duration

Following up - does anybody know the algorithm which determines when the page cleaners wake up and do work? I've got LRU_MIN set to 0 and LRU_MAX at 1, but I routinely go minutes with actual LRU dirty up to 5-7% before any cleaners start working. I'm using onstat -FR to monitor it and they're idle, not busy. Cheers Jay Walters wrote: > I know this is a common question, but I've tried to implement the common > wisdom and I'm still having trouble. > > I'm running IDS 7.3TC7 on Windows NT 4.0 sp3. I've got 290K buffers, 15 > LRUs and 5 cleaners. LRU_MAX_DIRTY is 1, LRU_MIN_DIRTY is 0. > Checkpoints are every 15 minutes. I only have two disks, and I've tried > to split the I/O down the middle, 1/2 on each. > > My environment has a fair number of writers and queries which need to > complete quickly (< 10seconds). > > I often see the cleaners idle (onstat -F) even with 10K dirty pages > (>3%). Something causes them to wake up and clean, but they don't > really keep the LRUs clean enough to keep my checkpoints short. My > checkpoints are taking 30-60 seconds which is way too long. > > If all the LRUs are over LRU_MAX_DIRTY, why don't the cleaners wake up? > Or are they on some type of timer? > > I would appreciate any ideas or comments... > > Cheers

7.3x page cleaner introversion (my description, not Informix'--they don't visit the LRUs as often as they did in 7.2x) has recently been acknowledged as bug number 110622. In article <37307383.3749F2AD@computer.org>, Jay Walters <jwalters@computer.org> wrote: >Following up - does anybody know the algorithm which determines when the >page cleaners wake up and do work? I've got LRU_MIN set to 0 and LRU_MAX at >1, but I routinely go minutes with actual LRU dirty up to 5-7% before any >cleaners start working. I'm using onstat -FR to monitor it and they're >idle, not busy. >Cheers >Jay Walters wrote: >> I know this is a common question, but I've tried to implement the common >> wisdom and I'm still having trouble. >> I'm running IDS 7.3TC7 on Windows NT 4.0 sp3. I've got 290K buffers, 15 >> LRUs and 5 cleaners. LRU_MAX_DIRTY is 1, LRU_MIN_DIRTY is 0. >> Checkpoints are every 15 minutes. I only have two disks, and I've tried >> to split the I/O down the middle, 1/2 on each. >> My environment has a fair number of writers and queries which need to >> complete quickly (< 10seconds). >> I often see the cleaners idle (onstat -F) even with 10K dirty pages >> (>3%). Something causes them to wake up and clean, but they don't >> really keep the LRUs clean enough to keep my checkpoints short. My >> checkpoints are taking 30-60 seconds which is way too long. >> If all the LRUs are over LRU_MAX_DIRTY, why don't the cleaners wake up? >> Or are they on some type of timer? >> I would appreciate any ideas or comments... >> Cheers -- W. Jim Jordan, Nortel Networks, Stop 29CA3A08 PO Box 3511 Stn C, Ottawa, ON K1Y 4H7 Canada wjjordan@nortelnetworks.com Opinions expressed are not necessarily those of Nortel Networks. Inbound spam filtering is in place. Don't send what I won't see.

Thanks for the information. I've poked my analyst at Informix, so we'll have to see if some bug #'s help him get me an answer or not. There is also another bug, 96929, which seems to be very similar. Cheers Jim Jordan wrote: > 7.3x page cleaner introversion (my description, not Informix'--they > don't visit the LRUs as often as they did in 7.2x) has recently been > acknowledged as bug number 110622. > > In article <37307383.3749F2AD@computer.org>, > Jay Walters <jwalters@computer.org> wrote: > > >Following up - does anybody know the algorithm which determines when the > >page cleaners wake up and do work? I've got LRU_MIN set to 0 and LRU_MAX at > >1, but I routinely go minutes with actual LRU dirty up to 5-7% before any > >cleaners start working. I'm using onstat -FR to monitor it and they're > >idle, not busy. > > >Cheers > > >Jay Walters wrote: > > >> I know this is a common question, but I've tried to implement the common > >> wisdom and I'm still having trouble. > > >> I'm running IDS 7.3TC7 on Windows NT 4.0 sp3. I've got 290K buffers, 15 > >> LRUs and 5 cleaners. LRU_MAX_DIRTY is 1, LRU_MIN_DIRTY is 0. > >> Checkpoints are every 15 minutes. I only have two disks, and I've tried > >> to split the I/O down the middle, 1/2 on each. > > >> My environment has a fair number of writers and queries which need to > >> complete quickly (< 10seconds). > > >> I often see the cleaners idle (onstat -F) even with 10K dirty pages > >> (>3%). Something causes them to wake up and clean, but they don't > >> really keep the LRUs clean enough to keep my checkpoints short. My > >> checkpoints are taking 30-60 seconds which is way too long. > > >> If all the LRUs are over LRU_MAX_DIRTY, why don't the cleaners wake up? > >> Or are they on some type of timer? > > >> I would appreciate any ideas or comments... > > >> Cheers > > -- > W. Jim Jordan, Nortel Networks, Stop 29CA3A08 > PO Box 3511 Stn C, Ottawa, ON K1Y 4H7 Canada wjjordan@nortelnetworks.com > Opinions expressed are not necessarily those of Nortel Networks. > Inbound spam filtering is in place. Don't send what I won't see.