Wouldn't it be documented somewhere that the
PWRDWNSYS *CNTRLD performs differently
from PWRDWNSYS *IMMED from a disk cache perspective?

That's the million dollar question. If I look at the help on PWRDWNSYS
you see nothing of the sort. You do see that
Note: When *IMMED is specified while the system is operating under
auxiliary power,
or if the delay time specified in the Controlled end delay time (DELAY)
parameter ends while the system is under auxiliary power...
To me that sounds like six of one, a half dozen of another. Same thing.

Numerous types of powering down the system are discussed at
and only those performed by control panel functions are flagged as cache

just mentions pwrdwnsys and makes no differentiation between *CNTRLD and
*IMMED. PDF version available at

In a hardware manual available at
says use *IMMED in talking about very general terms in starting/stopping.

And more searching at ibm.com for pwrdwnsys cache look like

PCI card
If you are installing 5580 or 5581, go to Type 5708, auxiliary-write cache
IOA for more .... When all jobs are complete, type pwrdwnsys *immed on an
OS/400 ...

PCI Card V5R3 - IBM
If you are installing 5580 or 5581, go to Type 5708, auxiliary-write cache
IOA for more .... When all jobs are complete, type pwrdwnsys *immed on an
OS/400 ...

So I'd love to see some IBM documentation that a *CNTRLD is better for
cache. Oh, sure, I strongly recommend bringing the system down to a
restricted state by first shutting down applications you know you have
controlled ways, like:
- ENDDOMSVR of domino servers
- Changing data queues for never ending programs which are written to
check them.
- Sending break messages to users imploring them to finish up and sign
And then after that running
and after you receive the message the system ended to restricted state
I do agree that *CNTRLD does allow applications that are written to check
for system shutdown to shut down more gracefully, but I'm not sold that it
does a magical job on cache.

Rob Berendt

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