But that perception is rapidly changing.
At its IBM Design Center for e-transaction processing opening in Poughkeepsie, N.Y., IBM last week demonstrated its Linux system running on the S/390 and hinted that plans are in the works to introduce versions of its software, such as the Websphere Web application server, optimized to run on mainframe-based Linux.
IBM is also testing and evaluating the viability of porting such products as the Lotus Domino Web server, the DB2 database and the MQSeries application messaging software, among other packages, to run on S/390 Linux, says Jeff Nick, an IBM executive. The company is planning to craft a Java Virtual Machine (JVM) specifically to let Java applications run Big Iron Linux.
Additionally, IBM is actively looking for partners to distribute and install Linux on mainframes, Nick says. The company already has posted a Linux port on its Web site to supplement that effort.
While Linux is a favorite among technical users, it is widely criticized as not being ready for the rigors of enterprise networks. But IBM and other companies are scrambling hard to change that perception. Big Blue is one of the biggest proponents of Linux and has been working steadily to make its server platforms and software support it.
For example, IBM recently detailed a prototype system of computers called Los Lobos that may soon let users run Linux applications at supercomputer speeds (NW, March 27, page 14). IBM's Netfinity PC server unit is actively promoting Linux as a viable, less-expensive alternative to Windows NT. The RS/6000 division has also made its servers Linux-friendly. And IBM is building a considerable service and support organization for Linux.
IBM executives say Linux on the mainframe gives the operating system an enterprise-class look and feel. For example, the operating system could exploit the high reliability and security of the mainframe, as well as its fast I/O technology and capacity to support thousands of users.
By supporting traditional enterprise-class applications such as DB2, Lotus Domino and other packages on the mainframe, Linux could rapidly become a viable option for large-scale business operations.
There is already considerable customer support for the Linux-S/390 coupling as well.
"Linux [on the mainframe] is a kick-butt Web server," says David Boyes of Dimension Enterprise, a data center design and testing firm in Herndon, Va. "You can do streaming video or audio, and the I/O hauls butt and takes names," he adds.
"I would say even IBM has been surprised at how well it's been received," says Harry Williams, director of technology at Marist College in Poughkeepsie. For the past year, he has been testing Linux on his mainframe for some Web applications, including a search engine, and has been pleased with its performance.
For its part, IBM says it's easy to run multiple copies of Linux as a Virtual Machine guest, which allows a copy of an operating system to run on the mainframe as if it were an independent server. In one test, a user claims to have run 40,000 Linux Virtual Machine guests on one mainframe CPU. IBM claims users can actually run more than that - up to 41,000. These servers can also communicate with each other inside the mainframe at 500M byte/sec, much faster than they could if they were physically separate servers in a LAN.
Properly exploited, Big Iron Linux could produce considerable cost savings. For example, Dimension's Boyes says, one of his company's customers, a telecommunications firm, needed to host Web sites for 400 clients. Instead of buying two or three Unix boxes for each of these customers - which would have cost millions of dollars - Dimension designed a system that would use 400 Linux servers on the customer's existing mainframe.
The customer was able to deploy these Linux servers rapidly at almost no increase in operations cost, he says. Nor did they need a high-priced management program to manage it, he says. The Linux guests are already in production, Boyes says, but he declined to name the customer.