RE: IOPless machines and multiple CPUs

Jim,

Not sure where I read this, but IBM I internal disks (SSD) will out perform VIOS.
VIOS adds overhead and an extra level for the I/O.
Our Production LPAR runs on our host P9, 18 arms, 100% SSD
Our R&D LPAR runs as a client off our Production LPAR, 70 Virtual arms, 100% SSD.
R&D performance matches production, better at times.

Paul


-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Jim Oberholtzer
Sent: Sunday, July 26, 2020 7:18 PM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: IOPless machines and multiple CPUs

True, VIOS come with PowerVM, and is about the same cost per core as VMWare, or less.

That’s the software. Now get the fiber And Ethernet switches to support the virtual environment and the cost goes up dramatically, so does the complexity.

For true production workloads that have any sensitivity to I/O, or the performance is critical, then VIOS is the way to go. Many IBM i workloads are just fine with IBM i hosting, and that’s far less complex, simple to set up, and easy to maintain.



Jim Oberholtzer
Agile Technology Architects

On Jul 26, 2020, at 12:01 PM, Roberto José Etcheverry Romero <yggdrasil.raiker@xxxxxxxxx> wrote:

Configuring an LPAR with more cores than licensed ends up with a
message saying that you are over entitlement but it still uses those cores.
One of the reasons I don't understand i hosting i is the economics of
the exercise. It is a lot more expensive to use IBM i to virtualize
storage/network than the almost free VIOS.
On a big machine you might need more than 2 entire cores for IO and
that gets expensive quickly.

Roberto

On Sun, 26 Jul 2020, 12:39 Patrik Schindler, <poc@xxxxxxxxxx> wrote:

Hello,

imagine a newer POWER machine with, say, four CPUs. IBM i is licensed
to one CPU, so I guess when you give the LPAR more than one, it won't
be used for running "normal" code. Right?

Does anybody know (and provide evidence) if a second assigned CPU
will be used as "helper CPU" for I/O? Not exactly an IOP, since this
involves drivers and other stuff. My thinking stems from the z-world
where processors can be freely configured to specialized tasks (I/O,
running Linux, running Java, …). The number of CPUs often influences
licensing cost, which probably was one of the reasons to invent this
feature in the first place.

Thanks!

:wq! PoC

PGP-Key: DDD3 4ABF 6413 38DE - https://www.pocnet.net/poc-key.asc


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