Re: Checkpoint durations

2008/11/28 Neil Truby <neil.truby@ardenta.com>: > IDS 10.0FC8W2 on HP-UX 11.31 > > I'm tuning IDS on quite a large system (18 cpus, 65g memory, Tier One SAN). > > I have BUFFERS set to 10,000,000 (ie 20g), and lru_max_dirty to 0.5%.(ie > 50,000 pages or 100m). lru_min_dirty is effectively zero. > > At times I'm seeingcheckpoints of 5 to 8 seconds. According to the > checkpoint tracer nearly all of this is waiting on disk. And my question > is: on a lareg OLTP system, does this seem reasonable throughput, a maximum > of 100m in 5-8 seconds?). > > Obviously I can reduce lru_max_dirty further, but I'm just interested to > know if this 12-20MByte/s rate is comparable to others' experience. > > Checkpoint statistics from other large users would be most welcome. > > thx > Neil > > _______________________________________________ > Informix-list mailing list > Informix-list@iiug.org > http://www.iiug.org/mailman/listinfo/informix-list > Neil P570, 4 x twin processors, 16 Gb memory total (not hugh but might help) 500 Gb fibre attached, sole use disk. 600,000 Buffers (= 2.4 Gb) LRU max 15 %, min 8%. Snapshot checkpoint around 7.7% dirty (5 mins from last) (= 185 Mb) with Fuzzy Checkpoints (are you fuzzy) < 1 second. Looking back over November my average checkpoints have been around 1 second. Any help Keith