Mainframe migration decisions overview: Mainframes have been a cornerstone of data center computing for decades -- they are scalable, stable, and can handle immense workloads without the "server sprawl" prevalent in many organizations today. But the advantages of mainframe computing are often overshadowed by premium hardware and labor costs, a complex and aging architecture, and pricey software licensing or maintenance expenses. In the face of these difficulties, some mainframe users are abandoning Big Iron and making the shift to open systems. IT research form Gartner Inc. predicted that 80% of today's smaller mainframe organizations will move away by 2010. Let's take a closer look at the considerations behind this shift, and examine some of the potential pros and cons of a major platform change.
Understanding the drivers
There are several compelling reasons to migrate off a mainframe and make the leap to open systems. One driving force may be corporate consolidation or acquisition, where one company must leave its mainframe to accommodate the data center integration with a new owner or parent company. A second important driver is time. Mainframes and their applications can be challenging to maintain. As the number of mainframe hardware and software maintainers dwindles, it is increasingly difficult to find qualified personnel to keep older systems and software running in a timely fashion.
But without a doubt, the most powerful force pushing users away from mainframes is money. A mid-level mainframe can cost hundreds of thousands of dollars; a top-tier mainframe can exceed $1 million. And beyond the initial acquisition, hardware upgrades, hardware maintenance, and software licensing are a substantial cost item. For example, Simon & Schuster Inc. expects $1 million a year in hardware and licensing savings by moving off its old IBM mainframes. Similarly, Tulane University in New Orleans sought to relieve $250,000 per year in software licensing fees.
Deciding what to migrate
Organizations that choose to migrate from mainframes to open systems will need to start by selecting the applications to migrate first. The choice is typically motivated by the biggest pain point. In some cases, an application may simply not be maintainable, and a new version for open systems is mandatory. Otherwise it's usually just a matter of which application(s) will save the most money, or yield the best performance improvement, by shifting them to open systems? In one example, the Indiana Bureau of Motor Vehicles (BMV) had to consolidate three customer databases from a 1970s-era mainframe without interfering with police or customer service.
The pros and cons
Any migration off of a mainframe to open systems should include a consideration of replacement hardware; how many servers (or more specifically, server processors) will be needed to perform the same jobs currently handled by the mainframe? Servers are far less expensive to acquire and maintain than a mainframe, but the addition of more servers often leads to server sprawl across the data center. Each server has to be configured and maintained separately, usually resulting in management headaches for IT administrators. As servers proliferate, differences in architecture and features can demand a broader understanding of hardware than mainframes. Many data centers are implementing server consolidation and server virtualization to attain the simplicity of centralized management and high utilization that mainframes offer by their very nature.
Security is another area that must be considered in any migration. Mainframes typically support security features natively through cryptographic coprocessor modules. Servers are not inherently secure, so security has to be added through software or hardware. Software encryption is typically processor-intensive, and is often a poor choice for data in-flight. Hardware encryption appliances can offer encryption at wire speeds, but appliances are costly, and may not be practical for broad deployment.
And then there's the unknown factor of bugs and performance problems during the migration process. In many cases, mainframe applications must be completely rewritten for a server environment, or adapted to meet the features available in a commercial software release. This usually leads to glitches in the early stages of a migration. This represents a serious risk for many organizations. For example, it took several weeks for Indiana's BMV to alleviate initial database integration issues affecting both police and drivers. Consequently, any migration process should add an ample amount of time for testing and refining before decommissioning the mainframe.
Microsoft in the fray
There is help out there. Formed in 2004, the Mainframe Migration Alliance (www.mainframemigration.org) represents a community of software vendors and service professionals ready to assist users considering the move to Windows platforms. The site offers guides, case studies, white papers, and discussion forums where users can learn and exchange ideas during their migration process.