Re: QJOCHRVC

[Bruce Vining <bvining@xxxxxxxxxx>]

Just a bit of a warning to anyone following this discussion.  In current
releases there is an undocumented program QJOCHRVC which controls how often
changes to journaled objects are forced to auxiliary storage.  In a future
release this program may become a formal API (that is in the Information
Center, officially supported, etc.) and as such experience some changes in
its authorization and parameter definitions.  Users of the current QJOCHRVC
program may want to keep track of where they code the program calls (and
minimize the places used) as they may get the opportunity to change them in
a future release.

Bruce



                                                                                
                                                      
                      "Charly Jones"                                            
                                                      
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This API is available back to V4R5...  There is a redbook called: 'Striving

for Optimal Journal Performance'
that contains a full explanation of the API and side-by-side benchmarks
with
performance numbers.  Here are some notes I got from a Google search using
QJOCHRVC:

You can now tune the journal recovery ratio (V4R5)
Background SLIC tasks: JORECRA (one per journal)
Sweep through main memory writing changed pages of journaled objs
Their mission is to cap the quantity of recovery time in the event of a
crash
The more journaled objects, the more aggressive these tasks become
They are driven by a "Recovery Ratio"
The default ratio is 50K
The tasks wake up as soon as 50K/ Numb_ Objs more Jrn Entries arrive
Every extra 10K added to the ratio increases abnormal IPL time by about 30
seconds
The higher the ratio, the less frequently journaled objects get written and

the
better the run time performance vs. longer potential IPL
It's similar to a default "Force Write Ratio" for journaled files
New API: Call QJOCHRVC 1000000
Increases recovery ratio to 1 Million (reduces background load by 95%)
Legal range is 10K to 2 Billion

Charly Jones
Gig Harbor WA
253 265-6244

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