IBM i for Power Systems, Power i, IBM i: What Do You Mean by That? A Primer (Rev 2.0)

ibm i a system designed for businessSince their introduction, there’s always been some confusion about what people mean when they say IBM i, IBM i for Power systems, and Power i. The terms are not interchangeable.

(First written on March 9th; substantially rewritten on March 16th)

Here’s my primer on when and how to use the terms IBM i, IBM i for Power, and Power i for people writing articles, blogs, case studies, white papers, etc. These are my own definitions and best suggestions for referring to or writing about the platform and the operating system. If you’d like to suggest modifications or another source for these terms, please post a comment here or email me at

Note: this is revision two of this article, based on reader and IBM i community suggestions. I’ll attempt to keep this article current as more information comes my way, and the content may change from time to time.

What is IBM i for Power Systems?

IBM i for Power systems is the official name for running the IBM i operating system on one or more IBM Power hardware machines. This is the name IBM mostly uses in its documentation though you may see some variations, such as:

All of these terms are found on IBM Web sites describing the combined IBM i/Power server offering, so they all can be considered valid ways to describe IBM i on Power Systems servers.

The reason you have to designate IBM i for Power systems is because IBM’s Power systems servers can also run Linux and AIX partitions and you have to differentiate which product you’re talking about.

The problem with these terms is that AFAIK, there is no hash tag that refers to IBM i for Power systems. I did a Twitter search on #ibmionpower and that yielded nothing. My recommendation is that when you’re tweeting about IBM i for Power systems, add the following hashtags to your tweets.

#IBMi #powersystems

This will allow your tweets to show in searches on either of these terms.

Also check out the #poweri hashtag listed below.

Power versus POWER

The interesting thing about using the term Power for IBM Power systems is that you will sometimes see the term in all caps (POWER). That’s because the word POWER is actually an acronym for Performance Optimized With Enhanced Risc chip set (thanks to Barbara Martinez for pointing this out to me in her comment on this article–see below). So depending on your style, you can spell any of the terms above in all upper-case ‘POWER’ or with the more readable upper- and lower-case ‘Power’. The downside to using the upper-case “POWER” is that PEOPLE MAY THINK YOU’RE SHOUTING THE TERM WHEN YOU USE ALL CAPS.

What is Power i?

Power i is a shorthand way for referring to IBM i for Power systems. This term is sometimes used by bloggers and other industry people. As far as I can tell, Power i is not an official IBM term but it comes in handy for blogging, articles, white papers, case studies, and other printed material, where you want to use a shorter term for IBM i for Power system so the material reads faster. Power i is also great to use in a headline where IBM i for Power Systems or one of its variants might be a little wordy.

Here’s an example of how you might use Power i in a blog post :

This solution runs on an IBM i for Power systems server (Power i).

Then you could use Power i as shorthand for IBM i for Power system server everywhere else in your document. Again, Power i is not an official term, but it is used by several industry writers, including myself.

When tweeting, you can also use the #poweri hashtag to refer to a Power i system. The only downside with using #poweri is that it has other uses in Twitter and searching on it may yield tweets you’re not interested in. But like the term Power i, the #poweri hashtag may provide a nice abbreviated way of referring to the platform.

What is IBM i?

rp_ibm_new_as40013-300x300.gifIBM i is the name of IBM’s business-oriented operating system that runs on IBM Power systems and PureSystems hardware. IBM i OS versions include i 6.1 and 7.1. IBM i 7.1 is the latest (at this writing), most modern version in this operating system family that traces its roots back to older operating systems, such as OS/400 and i5/OS. The OS/400 and i5/OS operating systems are predecessors to the modern IBM i operating system and should not be confused with IBM i.

Although IBM i shares an ancestral heritage with i5/OS and OS/400, IMHO it is incorrect to refer to i 6.1 and 7.1 as either i5/OS or OS/400. IBM i is the correct name to use when talking about i 6.1 or 7.1. Conversely, the OS/400 and i5/OS operating systems shouldn’t be referred to under the IBM i umbrella because they are pre-IBM i offerings.

The hashtag for IBM i is simply #IBMi. Some people like to capitalize it exactly like that but people will find your tweets on a search regardless of whether you use the #IBMI hashtag or the #ibmi hashtag.

Remember that although most IBM i installs run on IBM Power systems, you can’t use IBM i for Power systems, Power i, and IBM i interchangeably. That’s because IBM i also runs on PureSystems and Blade Servers.

Where do PureSystems and Blade Servers fit into this?

While IBM i for Power systems and Power i refer to running the IBM i operating system on IBM Power systems hardware, IBM i also runs on Blade Servers and PureSystems.

When running on an IBM POWER Blade Server, you may see the solution listed as one of the following:

I’m unclear on what type of hashtag to use for Blade Servers. If someone has any ideas, please let me know.

When I originally wrote this article, I said there is no corresponding term for running IBM i on IBM’s newer PureSystems hardware. I was wrong. IBM introduced PureSystems in 2012 and it is capable of hosting IBM i partitions on an IBM PureFlex system. But while (per IBM) there have been 10,000 PureSystems units shipped since 2012, it is unclear how many of these are capable of running IBM i.

Regardless, the proper way to define IBM i running on PureFlex hardware is:

IBM PureFlex Solution for IBM i

Again, this might be a little long to continually repeat in a technical document but it’s what IBM is calling the product and what should be used to properly refer to what IBM is selling. I personally like the idea of calling it Pure i but that is definitely not a sanctioned official term and I wouldn’t recommend using it.

Like IBM i running on Power Blade Server, there doesn’t seem to be a good hashtag for the IBM PureFlex Solution for IBM i. My best advice is to use the following two hashtags in any tweets on this combination to advertise that your tweet deals in both worlds.

#ibmi #puresystems

AS/400s, Power i, and IBM i

The tricky part is when you refer to IBM AS/400s. The AS/400 was an integrated machine (operating system and hardware) that only ran OS/400 in the 80s and 90s and was retired in 2000. IBM renamed and reintroduced the integrated platform a few times before 2008 as iSeries, System i, and i5 boxes, causing a lot of confusion in the marketplace. To make matters worse, IBM also renamed the operating system to i5/OS in the early 2000s.

In 2008, IBM merged the old AS/400-iSeries-System i platform with its System p platform that ran Unix to create the Power systems brand of hardware that ran both operating systems. It also renamed and improved the old OS/400-i5/OS operating system to IBM i at the same time. As said before, Power systems hardware can run AIX, IBM i, and Linux.

The confusion comes in with loyal platform users, writes, bloggers, enthusiasts, who continue to use the name AS/400, sometimes referring to IBM i for Power systems, Power i, and IBM i collectively as an AS/400. IBM no longer sells AS/400s. But the name lives on in the marketplace and there is a continuing discussion about why the IBM i community should stop using the name. This discussion is fought with passion from both sides.

My best recommendations

To be correct, my recommendations are:

1) IBM i should always be used when referring to the i 6.1 and i 7.1 operating system that runs on IBM Power hardware. It is also correct to call it i 6.1 or i 7.1, depending on the version

2) IBM i for Power systems (or one of its IBM-used variants) or Power i (non-IBM variant) can be used when referring to an IBM Power system machine that runs IBM i partitions. If you want to invoke its heritage, you can also slip in a reference to the old integrated AS/400 hardware and software…such as runs on the IBM i operating system (formerly known as OS/400) as I showed IBM did in the IBM i for Power systems section, so that people who aren’t familiar with the terms will understand that the product being sold will run on their hardware.

3) Use the descriptions for using IBM i with Blade Servers and PureFlex as shown above. However, I suspect there aren’t that many shops running in these environments so you may not need to refer to these products very often.

These are the definitions that work for me. For now, I won’t wade into the proper times to use the terms AS/400, iSeries, System i, i5, OS/400, i5/OS, etc. While these should refer only to hardware and software that isn’t sold anymore, people continue to use them interchangeably with Power i and IBM i.

What if I hear the old terms?

If you hear someone using the terms AS/400, iSeries, System i, i5, OS/400 or i5/OS when selling new software or hardware, the best thing to do (IMHO) is to understand they are probably referring to either the IBM i for Power systems or Power i platform (software and hardware) or the IBM i operating system by itself and move on. If you want, you can try to explain that they should be using the new terms and educate them. But this is not mandatory (note: others may disagree).

Generally it’s up to everyone to decide for themselves to use the correct terms referring to these products…unless you work for IBM and then there really is no excuse for calling it an AS/400 running OS/400 (you’re selling the thing, for Pete’s sake). Some business partners even like to use the old terms because that’s what their customers use. And I’ve been in plenty of shops where people still generically call it an AS/400. Until IBM and its business partners really get the branding message across, we’ll continue to see this confusion.

IBM no longer sells the old products so all you have to do is understand that IBM i for Power systems and IBM i are the new terms and go on evaluating whether what ever products or services people are discussing will work in your environment.

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About Joe Hertvik

Joe is the owner of Hertvik Business Services, a service company providing written white papers, case studies, and other marketing content to computer industry companies. He is also a contributing editor for IT Jungle and has written the Admin Alert column for the past ten years. Follow Joe Hertvik on Twitter @JoeHertvik. Email Joe for a free quote on white papers, case studies, brochures, or other marketing materials.
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4 Responses to IBM i for Power Systems, Power i, IBM i: What Do You Mean by That? A Primer (Rev 2.0)

  1. Bruce Hobbs says:

    Interesting that I just got a notice today from Apple that iOS 7.1 is available to download to my iPhone!

    I do like to be a bit retro and talk about V5R4 and V4R5 boxes as being part of IBM i. It’s really hard to keep all the names straight (I believe the Model 170 says AS/400e) so I prefer to use the current one for the older boxes as well. Just a personal preference.

  2. Hi, Joe:

    Re: PureSystems and IBM i.

    I propose “IBM i on Flex”.

    PureSystems is a product line. IBM i fits in under “PureFlex” and “Flex” offerings within that line.

    “IBM Flex System Enterprise Chassis” is the nomenclature for the hardware platform. As in, “IBM Flex System Enterprise Chassis”. You can get a Flex chassis, and add the bits and pieces you need, including Power Compute Nodes, x86 Compute Nodes, Storage Nodes (or external storage), Network, Storage, and software to run it all.

    PureFlex systems are a limited number of Flex bundles that includes pre-configured Power and x86 compute nodes and all the necessary supporting stuff (hardware and software) preconfigured in standard configurations. IBM refers to the “IBM i Solution for PureFlex”, and “PureFlex Solution for IBM i” in different materials.

    Inside a Flex System Enterprise Chasses, “Power Compute Nodes” are the boxes (they look like rack-mounted servers – there are pictures in the Redbook if you are curious) that contain Power processors and that run IBM i, AIX, and Linux. “x86 Compute Nodes” are the components in a Flex chassis that run Windows.

    So PureFlex or Flex, if you want to be specific about teh OS and the hardware it runs on, hardware, you are running “IBM i on a Power Compute Node in a Flex System Enterprise Chassis”. But that is a mouthful, and the “Power Compute Node: is implied, hence my vote for “IBM i on Flex”.

    Redbook: IBM PureFlex System and IBM Flex System Products and Technology

    • Joe Hertvik says:

      This reply is posted here and in the IBM i (unofficial) LinkedIn group discussion on this topic @ (if you’re a member of that group)

      Gary, I like your “IBM i on Flex” idea for designating a PureSystems Flex module that runs an IBM i partition.

      But I’d like to make another suggestion for designating IBM i running on a PureSystems machine.

      What if we called that Pure IBM i?

      It mirrors using Power i for IBM i on Power hardware and frankly, it just sounds cool to me. Kind of like that Pure Michigan marketing campaign of a few years ago.

      If that doesn’t work, IBM could always try PureSystems i, which might work too.

      What do you think?

  3. Barbara Martinez says:

    Joe – Thanks for the great discussion, clarification, and history lessons! There certainly are many ISVs and customers who still refer to the AS/400, just to differentiate and clarify the legacy of the platform on which they are running from other platforms. I also loved the comment about Apple’s iOS 7.1, which can lead to confusion for those who didn’t grow up with IBM midrange products.

    One small point, since we are discussing proper nomenclature, POWER should be capitalized, as it is an acronym for the Performance Optimized With Enhanced RISC chip set used in the hardware when, as you shared, IBM announced a single, common hardware platform to replace what had formerly been System i and System p.

    Finally, just to cause a chuckle, I have recently been working with a client who completely confused me in our first meeting, when they referred to their POWER i as their “Mainframe”! They are running IBM i on POWER, and not running z/OS on a a System Z, but to them , it is their enterprise wide system, not an x86 server or laptop!

    Thanks again! I will file this away for future use.

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