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The Great Debate: AIX Versus Linux

AIX Vs. Linux

In computing circles that I’m involved with, the debate rages on: AIX versus Linux. Administrators wonder, “Why would anyone want to keep running an OS that’s supported by one single vendor? Why wouldn’t you want to move everything to the shiniest and newest operating system and get away from ‘legacy’ enterprise computing?”

The odds are high that most AIX administrators have used both AIX and Linux and are well versed in both. Those that have a background in both OSs are better able to have informed discussions about the pros and cons of the environments compared to someone that has never used AIX, but that certainly doesn’t stop them from having an opinion.

Similar debates have raged on for years within the mainframe community. I’ve lost track of the number of times someone has declared the mainframe to be dead every time a new technology comes along. But when you look at the volume of critical transactions that still happen on the mainframe, it’s hard to believe that it’s going away any time soon.

AIX Advantages

The AIX debate is a little bit trickier. In many cases, it’s easy to port away from AIX and run on Linux or Windows. I may be a dying breed, but I still think that AIX is the premier UNIX flavor that is available today, chiefly because the hardware and OS have been coupled together to provide enterprise level reliability, availability and serviceability.

This isn’t an OS that’s running in a legacy or maintenance mode. The latest version of AIX, 7.2 TL0 was released in December of 2015, and AIX 7.2 TL1 was released in November of 2016. One of the highlights with TL1 is the ability to install service packs and technology levels without rebooting. The platform prioritizes high levels of uptime for critical workloads, and is well-suited for environments where downtime costs real money and reliability is a must.

For example, instead of bolting on a software-based hypervisor, POWER systems natively have hypervisors built into the hardware. By using VIOS and AIX together with the POWER hardware, you have an integrated stack that comes from one company. If something goes wrong, it’s much easier to get help from that single vendor. I’m not opposed to running Linux workloads; I just think that AIX is a more mature and robust OS. If given the opportunity to run Linux, I would consider POWER as a candidate to run my Linux workloads.

Breaking Down the Differences

It was interesting to replay the presentation that Andrew Wojnarek made to the Philadelphia Linux User Group on April 11. It’s nice to see that I’m not the only one who thinks that there are real advantages to the AIX environment.

Wojnarek supports a large fleet of machines—roughly half AIX and half Linux—and he says he has a pretty good feel for what it is like to administer both environments. He goes through the basics of AIX and why you would run it. Some of his arguments in favor of AIX include things like standardization—i.e., you can run the same OS on small servers and huge enterprise servers. Compare that to the subtle differences you will find between Redhat, SUSE, Debian, Ubuntu, etc.

He reminds us that when we are working with AIX we are in a ‘walled garden.’ He points out that there’s a standard way doing things with standard tools and commands. He talks about the built-in Logical Volume Manager, and the ability that we have with JFS2 to both increase and decrease the size of filesystems while they are online, which can be problematic with other filesystems on Linux depending on the type of filesystem that you are running. He talks about mksysb, the built-in tool to make backups that can be used to restore your server, either to the same hardware you took the backup from or to other hardware in your environment.

Device handling is a breeze on AIX. In Linux you have to echo values and edit files, whereas in AIX you just chdev a device. To discover something new, you run cfgmgr. To list attributes you run lsattr. Things are just easier and more consistent.

Wojnarek’s presentation isn’t an AIX love fest, however. He does discuss what he dislikes about the OS, and there’s a good discussion toward the end with the user group members. I recommend you watch the replay.

Some other advantages of AIX that weren’t in the presentation include the ability to use alt_disk_copy and alt_disk_upgrade to have online copies of your rootvg and to actually upgrade your running OS, which you can activate the next time you reboot. If you run into problems, you just reboot from the original set of disks.

Moreover, AIX has the advantage of having IBM PowerHA high availability software integrated into the OS at the kernel level and mainframe heritage virtualization baked into the hardware, not as an add-on hypervisor. AIX on enterprise hardware has built-in error reporting and diagnostics, and when call home is enabled, we might find an IBM CE dispatched to fix a problem before we even knew anything about it.

Consider Your Needs

Instead of all the arguing about which OS is better, sometimes it is worth stepping back and thinking about who is using it and why. Why do they want uptime and reliability? Why is it worth paying for hardware and software, compared to getting commodity hardware and a virtualization solution?

I’ve heard some great analogies over the years, including this one: Both a kayak and a container ship are seafaring vessels. One is better suited for taking large amounts of cargo across long distances. The smaller solution might get the job done, but you want to find and use the method that is suitable to the job at hand. Nobody would balk at spending more money on a container ship if that was the best solution. The same should hold true in the computer room.

Of course, there are some disadvantages with AIX. Perhaps you want to run the same flavor of Linux on your desktop and server—you can’t do that with AIX. Or maybe you want to learn AIX, but you don’t have access to education or hardware. The IBM Academic Initiative helps to fill the education void, but access to hardware is a legitimate barrier to those that want to learn more about the platform.

It can seem harder for someone to learn ksh if all they ever knew was a Windows or MacOS GUI and bash on Linux. There’s a learning curve with AIX, but that’s true of any OS—it takes time to become proficient.

I know the world loves Linux, but there are still many of us out here who love AIX. Linux users would be well-served to objectively listen to the key points in this never-ending debate to see if the advantages that AIX users take for granted might benefit their environments.

Rob McNelly is a Senior AIX Solutions Architect for Meridian IT Inc. and a technical editor for IBM Systems Magazine. He is a former administrator for IBM. Rob can be reached at rob.mcnelly@gmail.com.



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