Live from Sun — It’s Upgrades!

Peter Baer Galvin

One of the most difficult, challenging, risky, and downright unpleasant tasks a sys admin can perform is an operating system upgrade. There is a lot to plan, and a lot that can go wrong. If problems arise, restoring the system to its un-upgraded state also can be time consuming and carry its own risks. When the process is all over, the poor sys admin can look forward to testing the new operating system and tweaking it so everything that used to work does so again. Sun has come to the rescue with a new facility — Solaris Live Upgrade. This month in the Solaris Companion, I will look at Live Upgrade — theory and fact.

It must be frustrating to the engineers that work on an operating system release — they do all that work, and their users wait as long as they can to implement the new version. Sometimes the lag time is years. Some sites are still running SunOS 4.1.4 (and even earlier!). Of course, there are a variety of reasons for “rev lag”. One common reason is application compatibility. If an application is homegrown, no longer supported, or of unknown origin, it may have problems running on the newest release. Sun works hard to assure that each release is binary compatible with the others, so application compatibility is likely not the case here. The next most common delayer is support. Most sites only run supported applications in production. If the application vendor is not yet supporting the new operating system release, or requires an application upgrade for the application to be supported on the new operating system release, the operating system release stays put.

The final cause of “rev lag” is the difficulty of upgrading. No matter how compelling the features of the new release may be, the pain of performing the upgrade causes hesitation.