Re: Why host? Was: IBM i vs VIOS for Host Partition

No, only one, VIO Server. VIO Server presents disk units to IBM i in a very similar way that a hosted partition does. A partition that is hosted by VIO Server cannot itself be a host to another partition.

Jim Oberholtzer
Chief Technical Architect
Agile Technology Architects


On 4/18/2013 8:15 AM, Jack Kingsley wrote:

With VIO in the mix, system I doesn't own any of the storage?? So if you
create a dedicated LPAR then create I on I on top of that wouldn't you
essentially have 2 layers of disk virtualization.


On Thu, Apr 18, 2013 at 9:07 AM,<rob@xxxxxxxxx> wrote:

> Jim,
>
> Thanks. I thought the arms would be a better payback than the additional
> controllers.
>
> And, I meant the second paragraph to be totally independent of the first,
> like the first never happened.
> <snip>
> I consider this a good enough reason to host. Are there others? Well,
> perhaps VIOS san support?
> </snip>
> Meaning basically that if you want all disk on SAN isn't hosting required?
> Also asking for other reasons to host vs dedicated.
>
> 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: Jim Oberholtzer<midrangel@xxxxxxxxxxxxxxxxx>
> To: Midrange Systems Technical Discussion<midrange-l@xxxxxxxxxxxx>,
> Date: 04/18/2013 07:34 AM
> Subject: Re: Why host? Was: IBM i vs VIOS for Host Partition
> Sent by:midrange-l-bounces@xxxxxxxxxxxx
>
>
>
> Rob,
>
> The additional power of another disk controller will not mitigate the
> queuing that goes on inside IBM i for I/O, therefore unless you have six
> arms or more, you are reducing the available performance of I/O.
> (which might be OK in some situations where I/O is not a significant
> factor in the application, but it will affect backup/restore) What
> you'll have is a disk controller that's way under utilized. Put another
> way, you'll only be getting about 2% or 3% of your investment in the
> card back.
>
> In the case you cite, your better off creating a series of smaller
> virtual disk units so you wind up with as many as you can for the space
> you need.
>
> VIO Server really does not change the equation at all, it's just another
> method of virtualization.
>
> Jim Oberholtzer
> Chief Technical Architect
> Agile Technology Architects
>
>
> On 4/18/2013 6:17 AM,rob@xxxxxxxxx wrote:

> > We host some guest partitions because it reduces the cost of hardware.

> You

> > don't have to have a separate disk controller for each lpar. Part of me
> > has to wonder if 12 disk arms shared between the host and two guests

> would

> > be a better performer then 3 dedicated lpars with only 4 arms each. Ok,

> a

> > separate disk controller for each could blow that away though.
> >
> > I consider this a good enough reason to host. Are there others? Well,
> > perhaps VIOS san support?
> >
> > Let's take it to the extreme. Now we have a very large guest, over a
> > couple of TB. We did it this way because we wanted to do it "now" and
> > couldn't add another disk controller. The boss is saying when we get

> our

> > new hardware (which I think will be postponed quite some time due to the
> > business numbers I saw yesterday), that we will make that a dedicated
> > lpar.
> >
> >
> > 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 46755http://www.dekko.com
> > --