I would have to agree with what the consultant said. When working with disk you should always end the system controlled because it does flush the cache in the disk controller.
This bit me once many moons ago when inserting an LPAR into an 810 and I thought I could just move drives around. After about 8 hours on the phone with IBM and putting the drives back on the original controller, I was lucky enough to be able to live and fight another day. It might be better with today's code levels and battery-less controllers, but it's a hard lesson I carry with me so I continue to follow the procedure.
I'm not as restrictive to say it should ALWAYS be ended controlled, especially when doing things like scheduled IPL's, etc. But if I am doing hardware work, CNTRLD is the way to go.
Patrick Bingham | Principal Power Systems Engineer
Office: 402.965.2381 | Mobile: 402.212.2944 | Patrick.Bingham@xxxxxxxxxxxxx
Sirius Computer Solutions | www.siriuscom.com
14301 FNB Parkway, Suite 400, Omaha, NE 68154
-----Original Message-----
From: rob@xxxxxxxxx [mailto:rob@xxxxxxxxx]
Sent: Wednesday, January 16, 2013 6:36 AM
To: Midrange Systems Technical Discussion
Subject: Re: PWRDWNSYS
Malarky. While I do use *CNTRLD, even after ending to restricted state, please remember this; when you put a time limit on *CNTRLD after that time expires it does an *IMMED.
When you do a PWRDWNSYS *CNTRLD DELAY(120) when you are in restricted state it will stay there for 2 minutes, OR until you sign off your console session. Therefore, using the DELAY is NOT the trick when you are in restricted state - the trick is to sign off your console.
Now, as far as flushing cache, what kind of maintenance were they doing?
Replacing cache batteries? If so, RTM on doing so. To do this live (which I usually do unless the battery is swollen and requires an outage) the manual will talk you through the steps in SST to flush the cache and make the battery ready for removal. For just one sample battery pack on one card look at:
http://pic.dhe.ibm.com/infocenter/powersys/v3r1m5/topic/p7ece/stubcachebatterypack9117.htm#stubcachebatterypack9117__oscachebatteryibmi
Now as far as powering down the system as a whole, on my HMC there's an option, after I've powered off all the lpars, to power down the system itself. I think there's an option there that says power it off so that it's kosher to remove cache battery cards or not (or some such thing). I'd love to show you a manual link but all I can see (from somewhere it that above url) is "Select the desired power-off mode and click ok". And, I'm not inclined right how to power off a whole system just to step one through it. But given a little incentive for a couple of hours of after hours work... ;-)
Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600 Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com
From: Paul Fenstermacher <PFenstermacher@xxxxxxxxxxxxx>
To: "Midrange Systems Technical Discussion (midrange-l@xxxxxxxxxxxx)"
<midrange-l@xxxxxxxxxxxx>,
Date: 01/16/2013 04:38 AM
Subject: PWRDWNSYS
Sent by: midrange-l-bounces@xxxxxxxxxxxx
A former co-worker had a problem last week during a scheduled maintenance
window and the analysis afterward led a consultant to say this in his root
cause analysis report:
"Anytime you are doing any kind of disk work on a system you always want
to power the system down controlled. Ending the system "controlled"
flushes the disk cache from memory to disk, "immediate" does not do this.
I cringe when I see customers using *IMMED. 99% of the time the system
will come back up without issue, but that other 1% results in the type of
issue reported here. They took the time to end all of the subsystems to a
restricted state before issuing the PWRDWNSYS, which is the right thing to
do, but then powered down immediately. It's a common misconception that
ending the system controlled takes significantly longer to end. Once the
system is in a restricted state, it takes only seconds longer to end the
system "controlled" versus "immediate". The trick to using *CNTRLD is to
make sure you change the delay time to something like 5 (for 5 seconds)
rather than the default of 3600, otherwise you'll be waiting an hour
before the system starts powering down."
I have to say in 27 years of administering the platform in all its flavors
I've never done a PWRDWNSYS *CNTRLD and I have yet to have any problems
caused by that. Thoughts anyone??
Paul Fenstermacher | Sys/NW Admin,Sr | Corporate Systems - POWER Systems
Administration | Jack Henry & Associates, Inc.(r)
663 West Highway 60 | Monett, MO 65708 | Ph. 417.235.6652 | x177389 |
pfenstermacher@xxxxxxxxxxxxx<mailto:pfenstermacher@xxxxxxxxxxxxx>
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