Fast Commits and Write Behinds

From: wiz@telesis.COM (Karl Schendel)

On Jan 29, 23:42, Leyland Scar wrote:
> What is the best DBMS server configuration?
>
> 1) fast-commit flushes > write behind flushes
> 2) fast-commit flushes = write behind flushes
> 3) fast-commit flushes < write behind flushes

Well, I'm not entirely sure there is a "best".  But normally you would
try for

> 3) fast-commit flushes < write behind flushes

which implies that the write behind mechanism is doing something.
If the "fast-commit flush" number is = write-behind flushes then you
may want to try reducing the wbstart and wbend parameters.  read the
description of the DMF parameters in the installation & operation guide
carefully before you mess with them.
I think the main visible effect of ineffective write-behind is stalling
at the consistency point.  If you keep your write-behinds chugging then
the CP doesn't have as much work to do, and stalls the system for less time.

p.s. I've never seen f-c flushes > w-b flushes.  Is this possible?

-- 
Karl Schendel            Phone: (412) 963-8844
Telesis Computer Corp      Fax: (412) 963-1373
wiz@telesis.com
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