Re: IBM i vs VIOS for Host Partition

Since it isn't one of those things that really gets focused on but will
really matter to an admin, I wanted to emphasize Larry's comment about IBM
service. When you move to VIOS. IBM support is going to get a whole lot
more challenging. It's a single support area with just IBM i but once you
add VIOS to the mix you are kind of adding a different player and they
don't necessarily play well together. Your days of quick one stop support
shopping are over. And God help you if you add a SAN on top of it. That
hardware support is different than the hardware support for the Power
server. You will likely want to connect it via fiber and NPIV, probably
through a fiber switch (or switches if you have multiple VIOS partitions
which you will want if you go that route) and now if you have disk
connectivity issues between your i partition and your SAN, well, there's a
whole bunch of stuff in between and getting the right support person can be
a challenge and certainly won't happen quickly. And if it's a configuration
issue...that's a different kettle of fish and IBM will want to charge you
for that expertise.

One of the great advantages of the i is it's simplicity, but once you start
adding VIOS and SAN's you are throwing simplicity out the door. Not saying
there aren't advantages and reasons to do it (we did and we do), just be
aware of the price.

Tom Duncan (chief parade rainmaker)


On Wed, Apr 17, 2013 at 11:57 AM, DrFranken <midrange@xxxxxxxxxxxx> wrote:

I have done both, many times.

My largest IBM i host partition currently has over 30 client LPARs (A
couple Linux, a couple AIX, rest are IBM i.) The host uses 5913 RAID
cards and 24 15K SAS disk units in the host partition. POWER7.

Performance is excellent.
Rule 1) Have enough virtual arms.
Rule 2) Have enough physical arms.
Rule 3) Have enough virtual arms.
Rule 4) Have enough vSCSI links.
Rule 5) Have enough virtual arms.
Rule 6) Configure an I/O Buffer storage pool.
Rule 7) Have enough virtual arms.

I have several customers with VIOS on internal disks hosting IBM i clients.

1) IMHO Performance is not as good.
2) Maintenance of internal disks in VIOS, well, David would clobber me
for what I really think so I'll just say it's 'sub-optimal.'
3) IBM Service isn't anywhere NEARLY as schooled up on VIOS vs IBM i. In
one case this caused my customer to lose three IBM i client partitions.
Long story, ugly.

I do an entire presentation comparing VIOS and IBM i as a host
partition. You didn't want to hear all that so I'll quit now. :-)


- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 4/17/2013 12:34 PM, Kirk Goins wrote:

I am curious about the Performance differences, if any, when hosting IBM

i

on IBM i vs IBM i on VIOS. Are the 2 methods about the same? Wildly
Different?
Do I need more Memory or CPU generally speaking for one vs the other etc?

I don't need or want a discussion on what features/capabilities of each
method, but just how well the guest partitions perform. Looking for real
life experiences and any book type references..

Thanks

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