Re: What is a disk arm?

Rob raises an interesting question (one that, having hardware to play with
i plan on answering):
What happens when an LPARed system has to shutdown?
How does IBM i forward its "Start the UPS timer or call the Service
program" to its hosted partitions? (i've yet to do i on i hosting so i know
next to nothing about nws)
Does VIOS have a QUSPDLYTIM equivalent? can it talk to it's client
partitions or somehow monitor if virtual resources are in use or it's safe
to shutdown?
If the system doesnt have the "Shutdown system when all partitions close",
how do you initiate that shutdown?
All of those are questions that i plan to answer...


On Fri, Jun 14, 2013 at 11:40 AM, Buck Calabro <kc2hiz@xxxxxxxxx> wrote:

On 6/14/2013 10:18 AM, Charles Wilt wrote:

From the page...

"The following formula shows a worst case scenario.."

Understand and agree. I need to plan for the worst case, don't I? I
can't control how dirty the main store pages will be when the next
tornado blows through. :-(

Also
"The amount of time required to shut down a system typically is a small
percentage of this value."

Yes, quite true, and borne out by actual PWRDWNSYS commands on this very
machine.

Lastly it's important to realize you aren't doing a "suspend" as is the
case with a Windows PC. With a suspend in the PC world, all you are

doing

is writing out a copy of the memory to a reserved section of the disk.
With the i, you are updating all the objects on disk that have dirty

pages

in memory and doing additional house keeping as required. Not to mention
you are ending all jobs...

I'm not trying to do an IBM vs Windows comparison. It would be nice to
have the machine write that 32GB to a reserved area on disk and have the
next IPL update the dirty objects during startup when (typically) the
power situation has stabilised rather than take the time to do it during
a power-induced shutdown. Maybe the Power 8 machines will do that, who
knows? The platform keeps getting better and better. I've left reader
feedback so that the documentation can get better too.
--buck
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