RE: Automatic Performance adjustment

["Ingvaldson, Scott" <SIngvaldson@xxxxxxxxxxxx>]

Thanks Tom,

Those were my thoughts exactly.  I was just trying to figure out if there
was some piece to this that I was missing.

Scott Ingvaldson
AS/400 System Administrator
GuideOne Insurance Group

-----Original Message-----
date: Thu, 27 Feb 2003 20:31:01 -0500
from: qsrvbas@xxxxxxxxxxxx (Tom Liotta)
subject: RE: Automatic Performance adjustment

Scott:

I imagine the only reason "the majority" favored manual is because the
majority of those responding felt comfortable with manual tuning. Those who
most use auto-tuning possibly don't feel comfortable offering an opinion.

Personally, since somewhere in version 3 of OS/400, I've never seen a
production AS/400 that didn't run better on a day-to-day basis with
auto-tuning active. There'd be no rational way anyone could manually tune a
number of the systems I've worked with to get even decent results for more
than an hour or so.

As far as I know, there's no good reason not to auto-tune most systems,
especially if the system is configured to take advantage of it to begin
with. This means that subsystems should be configured with appropriate
subsystem pools, including private pools where needed, routing and pre-start
job entries should direct work to appropriate subsystem pools (tuning is
almost pointless otherwise), work is started in appropriate subsystems,
sufficient memory for shifting as needed should be available, basic
shared-pool settings are reasonable, etc.

And in a pinch, even if auto-tuning is active, you can still make manual
changes in order to react to exceptional circumstances. That item alone is
enough to suggest trying auto-tuning. By starting with an adjust at IPL and
automatic, you can get an initial set of pool sizes and activity levels to
begin baselining. Then switch to straight automatic once settings start to
fluctuate within a range.

If you need specific adjustments at regular times that anticipate change and
don't want to wait for auto-shifts -- end of day or start of day, e.g. --
then add job scheduler entries that cause major shifts, perhaps one or two
or more CLRPOOL commands plus related CHGSHRPOOL commands.

In short, I seldom have QPFRADJ at anything but 3 and I have no problem
augmenting it with manual action. I don't see it as either/or nor as
better/worse. Use both.

Tom Liotta