Mainframes and Docker Containers: Uses and Limitations

You can run Docker containers on mainframes. But should you? That’s a question that more and more mainframe-equipped organizations are bound to be asking following Docker’s recent announcement of Enterprise Edition support for mainframes.

If you follow mainframes and Docker closely, you probably know that it has long been possible to run containers on a mainframe. Docker’s recent announcement brings support for Docker’s Enterprise Edition containers-as-a-service (CaaS) platform to mainframes, but people have been running Docker on mainframes in other ways for years.

Docker on Mainframes: Benefits and Drawbacks

It’s clear, then, that there is serious interest in this topic. Why? The main reason is that mainframes provide a huge amount of computing computer.

If you already own a mainframe, and it’s underutilized for other workloads, using it to host Docker containers can be a great way to get more value out of it. The extension of Docker Enterprise Edition support means you can now manage your mainframe-based Docker environments as easily as any other environments.

Chances are, however, that few organizations are going to go out and buy a mainframe just to run Docker on it. If you’re in the market for massive infrastructure to host Docker workloads, the public cloud is a more obvious choice—unless you need on-premises infrastructure, in which case building a cluster with commodity servers is a cheaper and (in most cases) faster way to get up and running.

As for organizations that already own a mainframe, if it’s still up and running, it’s probably being occupied by legacy workloads. Many of these organizations will not have lots of extra mainframe capacity available to devote to Docker.

It’s worth noting, too, that to use Docker you have to be running Linux on your mainframes. This is easy enough to do, as IBM offers solid support for Linux on z Systems. But if yours are configured to run native z/OS rather than Linux, you’ll have to set them up with Linux before you can use Docker. And again, if you just want a bunch of Linux virtual machines to host Docker, it’s probably easier for most organizations to spin them up in the cloud than it is to set them up on a mainframe.

Conclusion

To be sure, there is value in being able to use Docker on mainframes. But the organizations that are likeliest to take advantage of this functionality are ones that already own mainframes and have nothing better to do with them. Those organizations probably represent a relatively small slice of the market because most companies are busy doing other things with their mainframes, and companies that don’t are not likely to buy one just to host Docker.

Christopher Tozzi

Christopher Tozzi

Christopher Tozzi has covered technology and business news for nearly a decade, specializing in open source, containers, big data, networking and security. He is currently Senior Editor and DevOps Analyst with Fixate.io and Sweetcode.io.

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