This article has originally been published in German at DataCenter Insider with the title “Wie wunderbar sind Mainframes – dank Linux“. A huge “Thank You” to chief editor Ulrike Ostler for the permission to publish the article in English at the SUSE blog.
Despite all the prophecies of doom, mainframes have never really “gone out of fashion”, and their lasting success is also closely linked to the triumphant advance of Linux, which has practically established itself as the standard in data centers. Banks, financial service providers, insurance companies, utilities, governments, hospitals, airlines and a large number of other public and private organizations count on the reliable and powerful data processing functions of IBM z Systems servers, which have been in constant use for decades. Many of these companies and organizations provide critical services that must be available 24/7. Even a mere minute of downtime is inconceivable to them. Consequently, their mainframes are one of the most important systems in their IT arsenal.
Innovation and New Concepts
The IBM mainframe is more topical than ever and is unchallenged in mastering a demanding balancing act: it draws optimum performance out of investment in hardware and applications, which, admittedly, is huge to begin with. The mainframe also continues to offer new options for enterprise computing year after year by introducing concepts and technologies that have a decisive impact on our economic and IT systems both today and for the future.
More than 95% of Fortune 500 companies currently rely on IBM z Systems servers, making use of business-critical applications that require fault-tolerant systems. These systems run without interruption year in year out and even their maintenance largely takes place during ongoing operations. The concept of business continuity was introduced with the first mainframe generation and is generally known as RAS – Reliability, Availability, Serviceability:
- Reliability refers to design features that recognize an error in a system, stop the system and then report problems instead of delivering incorrect results and calculations.
- Availability refers to design characteristics that enable the system to continue functioning despite the occurrence of a system error.
- Serviceability refers to the ease with which a system can be diagnosed in the event of errors; early recognition prevents or reduces downtime.
Moreover, the mainframe was designed with utmost security requirements to ensure maximum investment protection for companies and government institutions. This includes securing sensitive data by way of encryption mechanisms, protecting the privacy of users and a comprehensive audit mechanism with compliance reports. Since resilience and security have been a trademark of mainframe computing for over 50 years, many companies have discovered the advantages of z Systems as an enterprise security hub. It is with good reason that IBM z Systems servers have achieved Common Criteria Evaluation Assurance Level 5 (EAL5) certification—the highest security classification for commercial servers—from the International Standards Organization.
However, mainframes also represent yet another concept: Green IT. A single mainframe computer can replace dozens or hundreds of smaller servers. This not only lowers administration costs but also reduces energy, cooling and space requirements, while at the same time creating room for further growth.
The extreme Green IT capability of IBM z Systems is largely based on a technology concept that revolutionized the IT world. Developed for the first time in 1964 for IBM System/360, virtual machine technology—known today as virtualization—was a prerequisite for contemporary IT.
This leads us to the most “modern” IT concept, which to some extent was already implemented via the mainframe many years ago: cloud computing. Even before the cloud became a “new invention” it had been available on the mainframe for a number of years. The basic concept of cloud computing can be traced back to time sharing, the practice of joint using terminal computers and CPU time on a mainframe. This meant no more periods of inactivity on the mainframe and a greater Return On Investment.
And Now with Linux
In many organizations, current mainframes have more processing power than ever before since IBM z Systems provides a platform for high-efficiency computing. This is also due to one of the most important milestones in the five decades since the start of the mainframe era: the adoption of the open source operating system, Linux. Linux on z Systems combines all of the above-mentioned advantages of the IBM mainframe with the flexibility and open standards of an open source operating system. Today, Linux is the driving force behind innovations on z Systems due to its ability to facilitate quick, new solution approaches and reduce the time-to-market for many applications.
Even more important is the fact that Linux has generally become the engine for mainframe revival. Linux actually enables a large number of IT experts—who have grown up with Linux—to engage with mainframes. Why? The answer is simple: in principle, “Linux is Linux is Linux”, irrespective of the platform it is based on. Once again, an example of this is virtualization, since IBM z Systems is the perfect platform for consolidation via virtualization, for instance. For many IT specialists who are not experienced in working with mainframes or with z/VM—IBM’s hypervisor technology on mainframes—the topic of mainframe computers was generally taboo. For some time now, however, it has been possible to set up virtual machines on z Systems using KVM, the Linux virtualization technology (SUSE, for example, now offers full support for KVM on z Systems with SUSE Linux Enterprise Server 12 SP2). This makes accessing the mainframe a great deal easier for Linux administrators, since Linux—and KVM—behaves the same way on the mainframe as Linux behaves on x86.
A Bright Future
In the past 17 years, Linux has made a success story of the mainframe within the largest companies across the globe. Thanks to Linux, this success will be sustained in the future. Container technologies such as Docker, virtualization technologies such as KVM and projects such as the Hyperledger Blockchain Project of the Linux Foundation will ensure that IBM z Systems—with its extreme scalability and processing power—will continue to play a leading role in highly topical issues such as Internet of Things, microservices and digital data transformation.
Disclaimer: The text at hand has not been reviewed by a native speaker. If you find typos or language mistakes, please send them to me (firstname.lastname@example.org) – or if you like them, just keep them and feed them. 😆