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Re: Checkpoint durations

Posted in 2008

Topics: Performance & Tuning, Logging & Checkpoints, Platform-Specific Issues, Versions, Editions & End-of-Life

scottishpoet — — source: Usenet: comp.databases.informix

On Nov 28, 7:45 pm, "Neil Truby" <neil.tr...@ardenta.com> wrote: > 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 if large amounts of time are aiting on disk, how well does dd of large amounts of data to the disk perform without informix, is that acceptable?

↪ replying to scottishpoet
scottishpoet — — source: Usenet: comp.databases.informix

On Dec 2, 9:51 am, scottishpoet <drybur...@yahoo.com> wrote: > On Nov 28, 7:45 pm, "Neil Truby" <neil.tr...@ardenta.com> wrote: > > > > > > > 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 > > if large amounts of time are aiting on disk, how well does dd  of > large amounts of data to the disk perform without informix, is that > acceptable?- Hide quoted text - > > - Show quoted text - oops, should have rad thw wholethread! for seem reason i thought there had only been 1 response

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