-B parameter

[mattk]

Hi there,

Is there any information available around the use of the -b parameter. At present we have a 13gig Progress database working on a server that has 4gig of RAM available. At present the -B parameter is set at 2000 which we believe to be far too low. Hence we wish to significantly raise this.

Is there any calculation that can be done to work this out? Is there anything we should be aware of when raising this? Is there a limit that this can be raised to?

Any help that you could give would be much appreciated.

Regards.

 

[balebob]

Quick Calculation:

Physical Mem = -B value x Data Block Size

Ex.: Let assume that you data block size is 8192, the current -B that you have will use:

2000 x 8192 = 15.6 MB

Depend on what operating system that you use and if you are using 32-bit or 64-bit application/progress. For example, we run aix on 32-bit bit... Therefore, I can only allocated 11 mem segments to each pid unless I turn on EXTSHM which allows me to attached 21 segments to each pid. With 32-bit, I can only use my -B up to 2GB.

Any suggestion from other members are welcome.

 

[Casper]

There are many ways to figure out what is the best way. But I'm sure 2000 is way to low.
To minimise OS reads is your goal with setting -B. Rule of thumb some people use is 10% of Database size. But it all depends on the ditribution of the data, the way it is retrieved, activity etc....

Most times measuring will work best. Just set it higher and see how the system responses with promon, protop and OS tools.

Maybe you can take a look at Tom Bascoms BigBguestimator in protop:
http://www.greenfieldtech.com/articles/protop.shtml

Casper

 

[mattk]

Thanks for the advice guys this certainly makes things clearer.