Adding BUFFERS slowed Checkpoints

We had a system with which had a cache read hit rate of 94%. Originally, the BUFFERS parameter were set to 26,000 (i.e. 52Mb). Since the machine has 512Mb, we increased the BUFFERS to 132,000 (i.e. 264Mb). This improved the cache hit rate issue. However, it actually caused some problems. Our LRU_MAX_DIRTY and MIN_DIRTY are 3 & 1, respectively. Our system doesn't write enough to hit the MAX dirty (3% * 132000 buffers = 3960 dirty pages). Therefore, the cleaner threads aren't being used and all writing is being done at checkpoint time. (On average, we're writing about 500 pages per checkpoint.) These checkpoints have taken about 4-5 seconds. In our environment, that's too long. How do we shorten the checkpoints? I need them to be on the order of 1 second each. Are there kernel parameters that need to be changed when we increase the BUFFERS so high? We're running OnLine 7.22.UC1 under HP-UX 10.20. Thanks in advance for your help. David David Samson, Senior Database Researcher dsamson@ndsisrael.com NDS Technologies Israel Ltd. +972 2-589-4529 PO Box 23012 Fax: +972 2-589-4578 Jerusalem, Israel Cellular: +972 51 287 481