LRU's and CLEANERS (IDS 9.21FC1)

The manual says the following about LRU's and CLEANERS To monitor the percentage of dirty pages in LRU queues, use the onstat -R command. When the number of dirty pages consistently exceeds the LRU_MAX_DIRTY limit, you have too few LRU queues or too few page cleaners. First, use the LRUS parameter to increase the number of LRU queues. If the percentage of dirty pages still exceeds LRU_MAX_DIRTY, use the CLEANERS parameter to increase the number of page cleaners. My parameters have the following values - LRU_MAX_DIRTY 2 LRU_MIN_DIRTY 1 LRUS 30 CLEANERS 30 onstat -R gives me8587 dirty, 498979 queued, 500000 total, 524288 hash buckets, 2048 buffer size start clean at 2% (of pair total) dirty, or 333 buffs dirty, stop at 1% 0 priority downgrades, 0 priority upgrades According to what the manual says above, I need to increase my LRU's and CLEANERS. Is it still true if max & min dirty is set to 2 & 1 respectively ? To make a long story short, how many LRU's and CLEANERS do I need ? My write %cached is sitting at 93.78 (onstat -p) Dirk Moolman Database Administrator Reach Technologies "People demand freedom of speech as a compensation for the freedom of thought which they seldom use." - Kierkegaard

"Dirk Moolman" <dirkm@reach.co.za> wrote in message news:95dohr$onl$1@news.xmission.com... > > The manual says the following about LRU's and CLEANERS > > To monitor the percentage of dirty pages in LRU queues, use the onstat -R> command. When the number of dirty pages consistently exceeds the > LRU_MAX_DIRTY limit, you have too few LRU queues or too few page > cleaners. First, use the LRUS parameter to increase the number of LRU > queues. > If the percentage of dirty pages still exceeds LRU_MAX_DIRTY, use the > CLEANERS parameter to increase the number of page cleaners. > > My parameters have the following values - > LRU_MAX_DIRTY 2 > LRU_MIN_DIRTY 1 > LRUS 30 > CLEANERS 30> > onstat -R gives me> 8587 dirty, 498979 queued, 500000 total, 524288 hash buckets, 2048 buffer > size > start clean at 2% (of pair total) dirty, or 333 buffs dirty, stop at 1% > 0 priority downgrades, 0 priority upgrades > > According to what the manual says above, I need to increase my LRU's and > CLEANERS. Is it still true if max & min dirty is set to 2 & 1 respectively > ? To make a long story short, how many LRU's and CLEANERS do I need ? At SAP we recommend to configure LRUS and CLEANERS after NUMCPUVPS: LRUS = max( 4, NUMCPUVPS + 2 ) CLEANERS = LRUS + 2 After our experience we find performance advantages over the "traditional" settings, especially with low LRU_MAX/MIN_DIRTY setting and KAIO. HTH Christian -- #include <std_disclaimer.h>

Dirk Moolman <dirkm@reach.co.za> wrote in message news:95dohr$onl$1@news.xmission.com... > onstat -R gives me> 8587 dirty, 498979 queued, 500000 total, 524288 hash buckets, 2048 buffer > size > start clean at 2% (of pair total) dirty, or 333 buffs dirty, stop at 1% > 0 priority downgrades, 0 priority upgrades > > According to what the manual says above, I need to increase my LRU's and > CLEANERS. Not quite. The "2% or 333 buffs dirty" refers to each LRU queue, while 8587 dirty refers to the total number of dirty buffers in all the LRU queues (works out to avg of 1.7% dirty) Your LRU cleaning appears to be chugging along quite nicely in this snapshot. Rudy P.S. You may need to take more snapshots, especially at peak-time to reach an adequate conclusion.

Look mainly to your Bufwaits Ratio to determine if you have enough LRU queues. A BR <7% is ideal and >10% is death add LRUS to bring a high value down. Art S. Kagel Dirk Moolman wrote: > > The manual says the following about LRU's and CLEANERS > > To monitor the percentage of dirty pages in LRU queues, use the onstat -R > command. When the number of dirty pages consistently exceeds the > LRU_MAX_DIRTY limit, you have too few LRU queues or too few page > cleaners. First, use the LRUS parameter to increase the number of LRU > queues. > If the percentage of dirty pages still exceeds LRU_MAX_DIRTY, use the > CLEANERS parameter to increase the number of page cleaners. > > My parameters have the following values - > LRU_MAX_DIRTY 2 > LRU_MIN_DIRTY 1 > LRUS 30 > CLEANERS 30> > onstat -R gives me> 8587 dirty, 498979 queued, 500000 total, 524288 hash buckets, 2048 buffer > size > start clean at 2% (of pair total) dirty, or 333 buffs dirty, stop at 1% > 0 priority downgrades, 0 priority upgrades > > According to what the manual says above, I need to increase my LRU's and > CLEANERS. Is it still true if max & min dirty is set to 2 & 1 respectively > ? To make a long story short, how many LRU's and CLEANERS do I need ? > > My write %cached is sitting at 93.78 (onstat -p) > > Dirk Moolman > Database Administrator > Reach Technologies > > "People demand freedom of speech as a compensation for the freedom of > thought which they seldom use." > - Kierkegaard