The mainframe is the original cloud. Since the 1970s, big iron has shared a virtualized environment between hundreds...
of users and processes.
Just as on the cloud today, mainframe users weren't aware of the computer's location or its configuration; they just used the applications as a service. All the shared resources, centrally administrated, wrought maximum efficiency out of space and power. This matches today's definition of cloud computing.
Perhaps the most obvious example of a mainframe cloud today is IBM's Linux on System z (zLinux) guests on the mainframe hypervisor z/VM, running on Integrated Facility for Linux processor engines. Automation lets developers create customized zLinux images on demand. Administrators in production can bring the servers up or down as needed.
The z/VM hypervisor supports z/OS guests as well. For example, I've worked with fully automated z/VM scripts that initial program loaded an MVS image, started CICS, ran test transactions, gathered performance data and then shut everything down. Creating z/OS images is a little more complicated than zLinux, and z/OS brings in IBM's capacity-based pricing.
IBM also offers a zPDT personal development tool for running a z/OS image of x86 server hardware. With the right planning and infrastructure, enterprises can use zPDT to create many "little" mainframes for developers and systems programmers.
A little creativity could also extend the mainframe cloud concept to many popular subsystems.
IBM sells Batch Terminal Simulator (BTS) for IMS developers. Originally intended to test online IMS programs in batch, BTS now extends to Terminal Sharing Option users. Through BTS, each user has a copy of IMS, along with access to local or global databases.
DB2, IBM's relational database management system, tends to be monolithic, but supports a three-level table naming scheme. This means an IT shop could conjure a strong naming convention and a database utility infrastructure to enable developers to clone private copies of production databases.
CICS can play the mainframe cloud game too. Most shops run CICS online transaction processing as a started task, but there's no reason an application programmer can't submit an instance as a batch job. The IT shop needs some infrastructure to tailor, create and submit the CICS instances to the developers' specifications. But, once the job is submitted, each programmer has a CICS instance to mangle to their own delight.
About the author:
Robert Crawford spent 29 years as a systems programmer, covering CICS technical support, Virtual Storage Access Method, IBM DB2, IBM IMS and other mainframe products. He programmed in Assembler, Rexx, C, C++, PL/1 and COBOL. Crawford is currently an operations architect based in south Texas, establishing mainframe strategy for a large insurance company.
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