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Re: IDS 10 disk configuration

Posted in 2005

Topics: Storage & Space Management, Logging & Checkpoints

david@smooth1.co.uk — — source: Usenet: comp.databases.informix

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!

↪ replying to david@smooth1.co.uk
Art S. Kagel — — source: Usenet: comp.databases.informix

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. Art S. Kagel

↪ replying to Art S. Kagel
Neil Truby — — source: Usenet: comp.databases.informix

"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? I guess this isn't just an IDS 10 thing ...?

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