Re: IDS 10 disk configuration

Neil Truby wrote: > "Art S. Kagel" <kagel@bloomberg.net> wrote in message > news:42EFD602.60800@bloomberg.net... > >>david@smooth1.co.uk wrote: >> >>>At checkpoint time chunks are assigned round robin to page cleaners for >>>cleaning. >>> >>>ONE CHUNK WILL ONE GET ONE PAGE CLEANERS FLUSHING IT'S >>>WRITES AT CHECKPOINT TIME. >>> >>>We had a 60Gb chunk and someone was loading lots of data into it. >>> >>>5 minute checkpoint interval and checkpoints up to 6 minutes long! >>> >>>Just what I needed when running a program that inserts into temp >>>tables. >>> >>>My program went from 2 minutes to 20 minutes! >> >>Good point David. The solution would be to use fractional values for >>LRU_MIN/MAX_DIRTY to make sure that there are very few dirty pages at >>checkpoint time. Not a complete solution, but it will help with 'larger' >>chunks if not 'huge' ones. > > > > Are you both saying that an inevitable consequence of large chunks is long > checkpoint times at times of high update? At max peak, perhaps. Longer anyway. That's just one more thing to keep in mind when deciding to use larger chunks. Similarly, it occurs to me, you would increase checkpoint times by using very large page sizes, unless you adjust the LRU_MIN/MAX_DIRTY settings for that buffer cache, since the same number of dirty pages will require more physical IO than for smaller page sizes. I guess tuning in 10.00 gets more complex, not simpler. > I guess this isn't just an IDS 10 thing ...? No it affects 9.40 also. At least the large chunk part does. Art S. Kagel