Beautiful Architecture – Guardian: A Fault-Tolerant Operating System Environment (Chapter 8)

By far, the saddest part was that their Tandem Beer Bust was destroyed! In all seriousness, it seems that the Tandem computers with the Guardian OS, collectively, provided a fault-tolerant environment. Although it highlighted the Guardian having process pairs (a primary and a backup in "hot standby" state) the hardware also gave way to much of this fault-tolerant environment with its multiple processors, multiple disk controllers, and multiple busses as shown on page 177. This provided their biggest distinction with conventional computers in that "no part of the system can fail without bringing down the system". In short, they really just provided redundancy in several areas of the hardware and OS. Redundancy, as we all know, leads to more costs but I was surprised that they didn’t mention the enormous power consumption that it required. If you throw in the fans that were located below the I/O controllers, then that's a lot of juice needed to keep the 6 foot processor cabinets cool. Also, redundancy doesn't ensure that data won't get corrupted if both primary and redundancy components fail.

I didn't really think there were any advantages to their naming conventions. I mean, when you have different formats for unpaired system processes, unpaired user processes, named user processes, and network-visible processes, it just becomes a real burden on the programmer. This lack of consistency leads to more bugs and security holes (as shown by the ability to steal the system's root password) that could ultimately lead to the demise of a system.