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Linux mainframe faces off against the server farm

It's a faceoff: Linux on z vs. other server distributions. See what the pros say about Linux mainframe and decide if it's right for your IT shop.

Should you deploy Linux on the mainframe?

There are plenty of positives and negatives that make it clear that a Linux mainframe isn't right for all IT shops. Two experts go head to head on how to decide what's right for your data center: Linux workloads on a mainframe or running them in a distributed server environment.

Pro: Linux on a mainframe

Get reliability, availability, security and performance by putting workloads on the mainframe.

"Simply put, if you are looking to run a large number of virtual machines in an environment with tons of memory, in an environment that is extremely energy efficient and in an environment that is highly manageable -- [IBM] System z should be evaluated," said Joe Clabby, president of Clabby Analytics.

Mainframes guarantee safety; with an Evaluation Assurance Level of 5+, mainframes have the highest security rating. The newest version of the Linux kernel can run mission-critical applications without the risk of breach or disruption. Securing centralized mainframes is easier than securing hundreds of distributed Linux servers; administrators have to attend to each network interface individually on each box and lock down all access points.

The mainframe has higher resource use rates than distributed server environments. Linux processors on the mainframe handle workloads instantly and efficiently. Running Linux workloads on a System z mainframe is cheaper than on a distributed server because software license fees are coupled with processor cores.

Virtualization and provisioning techniques also increase mainframe use rates. Keep the mainframe busy and it will provide the highest return on investment.

Against: Linux mainframe might not be for you

If you don't want a Linux mainframe, don't worry. You aren't alone, according to Robert Crawford, a systems programmer and SearchDataCenter contributor. A Linux mainframe isn't right for everyone.

"We couldn’t make the economics work due to sweetheart hardware and Linux vendor agreements, along with our distributed environment already being aggressively virtualized. Finally, we couldn’t make large pieces of our infrastructure tooling work on zLinux," said Crawford, which is why he didn't deploy Linux on z.

IBM offers the Integrated Facility for Linux (IFL) engines, making the Linux mainframe a reality. But how valuable is this processor?

Consolidating many workloads from underused servers onto fewer mainframe IFLs makes for a successful migration to z/Linux. But hypervisors are increasingly consolidating server workloads -- even mission-critical ones. This makes migrating to IFLs less attractive because the economics of the Linux mainframe conversion change significantly.

Then there are concerns with performance and price. Not all Linux operating systems work similarly on mainframe processors, and enterprise editions differ in price as well: Linux distribution providers price the mainframe software uniquely.

The hardware for the mainframe and other server infrastructures also require different skill sets and expertise. Commodity hardware is less expensive than mainframe processors.

Eliminating the mainframe could help eradicate office politics. Talk about moving workloads between platforms and an IT war will break out. An impartial study on a workload that includes all parties is the best approach. How do you decide which platform is right for the task? Put the workload on z/Linux and on a Linux server cluster, and see how it runs.

Disclaimer: Every workload is different, as is every business. Use these counter arguments as a starting point to make best decision for your IT organization.

Next Steps

IBM server woes continue to struggle

How the Novell Attachmate deal affects SUZE z-Linus shops

Dig Deeper on IBM system z and mainframe systems

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Would you put a Linux mainframe in your IT shop?
I work for a large university and "the management" decided against zLinux for the wrong reasons.

1) Our internal customers prefer windows based apps so they  didn't want to port apps from x86 to IFL architecture which I'm told isn't a biggie unless you have lousy developers.

2) Mainframe costs (zOS) where too high. They never bothered to attempt and re-negotiation of sw licensing costs w/IBM and other vendors .

3) Never attempted a zLinux POC even when IBM offered it to them for free.

So now our Z is turned off and we're still paying thru the nose for the large carbon footprint.  
Naturally, we are against vendor lock-in associated with Mainframes, while it may require more resources to handle a commodity solution, the support contracts alone will cover that. Add to that agility of changing commodity components and one may find that one is stuck with an aging behemoth that is to expensive to upgrade and not the right tool for the business needs of the company.  A mainframe may be ideal for certain types of tasks, but inadequate for others, but one loses the option to tailor the environment for the needs. Marc Rotzow, CTO Open Source Storage
My company has invested in a Mainframe running IFL's and we have joined this platform with our Power, AIX and X86 environments. Much of what Richard says in his response is very true, the barrier to deploying on Z is mostly fear not logic.
Marc's comments are also really valid, in our experience so far the wind is changing and the  open source product community and some of the larger Linux distributions are showing that flexibility is there and they do have a vested interest in this market.
We have a number of open source ISV's using the Z platform and much of the functionality we wanted is being realised 
IBM would love everybody to run everything on mainframes. They want to lock in people with proprietary hardware. So called IFLs don't include anything out of the box except CPUs. You have to pay separately for Memory, storage. This whole notion of running 100's of VMs on a single IFL is a pipe-dream. Real workloads require lot of compute / IO bandwidth. Once you are past the marketing slides, IFLs are not economical at all. The only time they make sense is when you have purchased a mainframe and don't have sufficient work loads on it. Otherwise it is does not make sense for a new customer to buy IBM mainframe to run LINUX.