Postscript

Two months after this article was written, the system has gone “live,” and has a large number of active users. We also found some bugs by stress testing the system in a production environment. Our experiences were surprising:

• So far, we have found two separate operating system bugs in MVS. One made it impossible for the CICS region where our software runs to be shut down, due to a problem with the TCP/IP socket library. Another has to do with memory not being properly freed up by the standard C function library. So much for the robustness of mainframes!
• Unsurprisingly, we found and fixed a number of small bugs in our own software.
• To date, we have had no problems, and have found no bugs, in the Linux servers.

What is interesting here is that the least expensive component of the system and the one with no formal vendor support has been the source of the fewest (i.e., zero) problems. Much more expensive systems and much more expensive vendors (us) have yielded more troublesome systems than Open Source software.