Re: SMP experiences

[Vern Hamberg <vhamberg@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Rick

If you are using a lot of SQL, SMP can be greatly beneficial. The optimizer 
has all kinds of parallel processing methods available. Check "Database 
Performance and Query Optimization" under Database at InfoCenter and search 
the PDF on the word "symmetric". It also gives the most benefit in 
CPU-bound apps.

Know that order is unpredictable when using parallel methods. Have to use 
ORDER BY if the order matters.

If not using SQL, the main advantage comes in index maintenance, I believe. 
As per the above manual:

> Consider SMP and parallel index creation and maintenance:
>
> Symmetrical Multiprocessing (SMP) is a valuable tool for building and 
> maintaining indexes in parallel. The results of using the optional SMP 
> feature of OS/400 are faster index build times, and faster I/O velocities 
> while maintaining indexes in parallel. Using an SMP degree value of either 
> *OPTIMIZE or *MAX, additional multiple tasks and additional server 
> resources are used to build or maintain the indexes. With a degree value 
> of *MAX, expect linear scalability on index creation. For example, 
> creating indexes on a 4 processor server can be 4 times as fast as a 1 
> processor server.

Another place where SMP is used is in CPYFRMIMPF (the DataLoader):

> Use the Copy From Import File (CPYFRMIMPF) command to copy the data from 
> the import file to your iSeries database file. If you have the DB2 UDB 
> Symmetric Multiprocessing product installed on your system, the system 
> will copy the file in parallel.

You could look at the Performance Management Resource Library
<http://www-1.ibm.com/servers/eserver/iseries/perfmgmt/resource.htm>
for more info. Especially look at the Performance Capabilities manuals.

Also, take a look at <www.iseries.ibm.com/db2> and dig around.

HTH

Vern

At 09:07 AM 6/24/2003 -0500, you wrote:
> I am looking at our use (or lack of use) of Symmetric Multiprocessing on our
> production iSeries.  Specifically I am researching how SMP may be used to
> improve our nightly batch processing.  We have an 8xx with 16 processors.
>
> Does anyone have any experiences or advice they would be willing to share?
>
> TIA,
>
> Rick