Re: SETOBJACC status

Jim,

Are you sure about that? I've never heard the file can't be updated.

Sure the system will have to flag the updated pages as "dirty" and save
them to disk at some point. But that would have to happen regardless of
where the changed page is. Nor does that write to DASD automatically
remove the page from the pool.

In fact this document
https://www.ibm.com/support/pages/setobjaccclrpool-commands says

There will be few, if any, database reads once the file has been preloaded
using SETOBJACC. Database writes will still be handled the same way.
Database writes are usually done asynchronously to the user's job by system
output tasks. Since database reads are processed much faster once a file is
preloaded, database writes will be done more frequently by a program that
is also doing updates, adds, or deletes. This may cause occasional overrun
of the system output tasks, resulting in more database writes being done
synchronously rather than asynchronously to the user's job. Therefore, the
job may not perform as well as expected. However, the job will still be
faster when using SETOBJACC.


Charles



On Fri, Jul 16, 2021 at 4:16 PM Jim Oberholtzer <midrangel@xxxxxxxxxxxxxxxxx>
wrote:

If there so much as one write to that file, it will be pushed out of
memory by storage management. That’s to ensure the data integrity of the
file, Read only, that works, but don’t open it for input.

Jim Oberholtzer
Agile Technology Architects

On Jul 16, 2021, at 4:23 PM, Steve Pavlichek <spavlichek@xxxxxxxxxxx>

wrote:

Mark,
We did create a private memory pool for this one object. It’s only about

200MB and we have 1.5TB memory. This one file has A LOT of IO to it.

From: Mark Waterbury<mailto:mark.s.waterbury@xxxxxxxxxxxxx>
Sent: Friday, July 16, 2021 4:54 PM
To: Midrange Systems Technical Discussion<mailto:

midrange-l@xxxxxxxxxxxxxxxxxx>

Subject: Re: SETOBJACC status

Steve,

That object will NEVER be "pinned" in memory when using SETOBJACC.

SETOBJACC does NOT "PIN" anything into memory. That is why you should

create a separate private memory pool, so that when you issue SETOBJACC, it
will do a "BRING" to bring (page in) the entire object into that memory
pool. But then, subsequent to that, if any other demands on that same
memory pool cause pages to be "stolen" -- well, TOO BAD, SO SAD...

(If it did do a "pin" that could be VERY BAD for overall system

performance.)

For more details or how you can write your own program to issue the MI

instruction SETACST (Set access state), see:

MI instructions can be written in OPM MI assembler or you can embed them

as built-in functions in any ILE language (C, CL, RPGLE).

Hope that helps,

Mark S. Waterbury

On Friday, July 16, 2021, 04:02:56 PM EDT, Steve Pavlichek <

spavlichek@xxxxxxxxxxx> wrote:

Is there a way to show what objects are pinned to memory with the

SETOBJACC command or a way to prove that an object you want pinned is
actually pinned to memory?

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