Basically think of it this way: There are no disks, there is no disk
cache, it's all a big flat memory space. The objects live in this memory
space. During a save the objects are copied from it to backup media. How
that actually happens (because we know the big flat memory space is an
illusion perpetrated by the LIC) we don't care about.
Except that we're technical people who are curious and want to know
about such things.
- Larry "DrFranken" Bolhuis
On 1/17/2013 10:33 AM, Paul Fenstermacher wrote:
A save saves the object and all the data associated with the object so if some of that data is still in the disk cache the save somehow has to save that data also. I believe the question has been answered. Thanks.
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
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Thursday, January 17, 2013 9:20 AM
To: Midrange Systems Technical Discussion
Subject: RE: PWRDWNSYS
Well, I disagree that even a PWRDWNSYS *CNTRLD even completely flushes cache.
But, more importantly, I disagree that the save commands are invalid unless cache is fully flushed. A save saves an object. The OS doesn't care if the object is in cache or on disk. It saves the object. It's not like the save says "let's go read the VTOC and save sectors x-y associated with this object and write those to tape". Now, if your CE is doing a gig-mig to do a drive migration that may be a little different. Heck I would be surprised if the save didn't use the cache itself to speed up the save process.
IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600 Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
Kendallville, IN 46755
From: Paul Fenstermacher <PFenstermacher@xxxxxxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>,
Date: 01/17/2013 10:06 AM
Subject: RE: PWRDWNSYS
Sent by: midrange-l-bounces@xxxxxxxxxxxx
This topic ended up, as it should have, focused on flushing cache. As I
think about it, if ENDSBS *ALL does not completely flush the disk cache
and it isn't completely flushed until a PWRDWNSYS *CNTRLD is done then
every restricted state backup ever done is potentially invalid UNLESS all
the save commands somehow save the information in the disk cache.
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 |
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Sue Baker
Sent: Thursday, January 17, 2013 7:52 AM
Subject: Re: PWRDWNSYS
On 1/16/2013 12:52 PM, Jeff Crosby wrote:
Would the cache batteries have held properly from whenever the UPS
batteries went dead until 1pm?
Yes, the cache batteries should have held the contents of the write cache
for the few hours you were without power.
The adapter slot must be powered on in order for the batteries to charge
from electrical power. Depending on system type, this may mean the LPAR
must be active (to DST at least) for the trickle charging to occur.
With the cache batteries in normal condition, the contents of write cache
should not be lost if you have to go multiple days without power.
IBM Americas ATS - Power Systems
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