Re: Slow system ?! - using Informix 7.x on Sun Sparc 1000

George Kydes wrote: > > My company has a customer which is running our app (uses informix for > RDBMS) on a Sparc 1000. The system has the following specs: > > - 4 CPU's (don't know CPU speed), 512 MB RAM, 8 GIG of HD (6 GIG for > informix database, 3 2.1 GB HDs). > - This system averages 600,000 transactions per day. > > Here are some quick "onconfig" parameters: > > - rootdbs is 500 MB > - physfile is 10 MB > - logsize is 10 MB and there are 5 of them > - initial shmem 16 MB, additional shmem 16 MB, no bound set > - checkpoint interval is 300 seconds > > We are experiencing a problem where the system runs slow. After a > quick examination, it was seen that under normal operation is > checkpoint was being performed about every 3 minutes with each one > lasting about 45 seconds. This appears to be the major problem as to > why database access is slow. > > I appears that the physfile space is filling up too fast and reaches > the 75% threshold level too quick. So, I am thinking of raising it > from 10 MB to 50 MB (1/10 of the rootdbs where it resides). Does this > seem reasonable? Are there any general guidelines as to the sizes of > both physical and logical logs (without having to figure out > userthreads and critical sections, etc..)? This seems reasonable. The most accurate way to tune the size of the logs is during normal loading, and an on-going tuning process. > Also, are there any other ways to reduce the amount of time it takes to > perform a checkpoint? Gauging from other systems that even have higher > volume, a checkpoint should only take a couple of seconds! Tune the LRU_MAX_DIRTY and LRU_MIN_DIRTY parameters. Reducing these will increase LRU writes and hence decrease chunk writes, thus reducing the time taken by a checkpoint. > On a related topic, does anyone recommend the informix classes on > tuning Online and in your opinion would a person be able to configure > and tune a large scale system running informix after taking such a > course (assuming that person had practical work experience using > informix)?? Yes and yes. But then I am biased, as I give them. ;-) Just remember, nothing can replace experience. You won't become an expert over night. Cheers, -- Mark. +------------------------------------------------------------------+ |Mark D. Stock - The West Solutions Group http://www.west.co.za | | The Informix FAQ is at http://www.iiug.org | |mailto:marks@west.co.za +-----------------------------------------+ |Tel: +27 11 803 2151 |If it doesn't work, force it! | |Fax: +27 11 803 2189 |If it breaks, it needed replacing anyway!| |Cell: +27 83 250 2325 |Well, that's how I code anyway! | +------------------------+-----------------------------------------+