Re: Disk controller failure?

Power6 Hardware didn't use IOP either, you could have legacy PCI exps with
them but not on the CECs. And i think they finally died off in Power7.
There was a time when CPU resources where very limited and in those times
the decision was made to offload I/O tasks to dedicated cards (it also
allowed to IPL parts of the machine without doing a full system IPL). Thats
why up to Power5 hardware you always had an IOP before the IOA. Nowadays
you have virtual IOPs on each slot and it's all handled either by the CPU
or the chipset.
Since you're working with a 520 you are still in the IOP era (to be fair,
some cards started having dual-mode but as i said before, better to take
the easy way and have them under an IOP).

Best Regards,

Roberto


On Fri, Jul 11, 2014 at 4:44 PM, <rob@xxxxxxxxx> wrote:

Some IOA cards, in some situations, require a second card, an IOP.
IOA = Input/Output Adapter
IOP = Input/Output Processor.
The IOA will have the physical ports to hook up cables and is usually to
the right of the IOP, which has no ports.

Here's an example:
WRKHDWRSC *STG
CMB03 2844-001
DC02 5704-001
TAPKVL01 3576-05B

2844 is the IOP
5704 was a scsi IOA
3576 was a SCSI tape drive.
Cable went from the 5704 to the external tape drive.

Some of the same cards may have needed an IOP only if used by IBM i, but
if used by Linux, could not use an IOP.

I skipped the power 7 but on the Power 8 you can not use any IOP's.


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: Nathan Andelin <nandelin@xxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date: 07/11/2014 03:23 PM
Subject: Re: Disk controller failure?
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>

The 2844 is an IOP

Okay, but I don't know the difference between a disk controller and an
IOP.
I just understand that they fit in the PCI slots and communicate between
the disk and the processor ;-)
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