Via email, I've received a somewhat fortuitously timed press release that discusses the lengths to which Microsoft and NEC have partnered to create a solution known as Active Upgrade -- a fault tolerant solution that allows Windows server administrators to avoid reboots after upgrades or patches are installed. According to the press release:
NEC Solutions (America), Inc., a premier provider of integrated solutions for the Connected Enterprise in North America is introducing an advanced High Availability upgrade solution, Active Upgrade™ for NEC’s latest Fault Tolerant (FT) next generation server series, the Express5800/320Ma. With Active Upgrade technology, businesses can achieve a higher-level of continuity during planned downtime situations, which include installing critical hot-fix operating system patches, Service Packs, applications, and system software....The Active Upgrade software enables businesses to apply online software and system upgrades without the need to reboot.
The timing is uncanny considering the blog I just posted the other entitled Back to the virtual driver future (aka: What's with all the reboots?). In that blog, I complained about how one of the benefits of 32-bit processors that we grew to love was the elimination of the Windows reboot everytime a new driver or piece of software was installed. Somehow, that benefit has faded into the wind. The blog has drawn commentary from a variety of quarters citing Linux's longstanding ability to stay up and running despite driver, application, and even kernel patches. Here's a sampling of the comments:
Dietrech: With SuSE and other Linux Distros, rarely does installing a driver or, for that matter, a kernel patch, require a system reboot.
Carme: Linux doesn't ever need a reboot, unless something goes wrong. Drivers can be loaded and unloaded on the fly at any time. Installing a new version of a driver is just two steps, unloading the old and loading the new. Installing or removing software never requires a reboot. There is no operation that either a user or an administrator can do that requires a reboot, other than installing and running a new kernel or some major hardware change.
dragosani: ...I have a few linux servers that have been up for around 1.5 years (that is when they were installed and setup). They were down only one time in that period because of an extended power failure that drained the ups battery. Updates are not a problem for those machines. I have patched the linux boxes serveral times and didn't need a reboot....
Michael Kelly: With Linux I only reboot when I compile a new kernel, and even then I only compile new kernels when I know there is a security issue with something compiled directly into the kernel, or if there's a new feature I want. Otherwise I recompile the modules only and reload them.
jimbo: ....why does a Norton Antivirus update, or Turbotax application install require a reboot? Are they just being lazy, and require the roboot "just to be sure" or is there a critical design error in windows which cause this phenomenom? Are registry updates deferred to a reboot?....
I can't address jimbo's TurboTax question. But with antivirus utilities, I'm relatively certain the reboot is required to make sure the shields are fully raised (eg: they're ready to intercept malware in a variety of OS hotspots) in a way that no malware can sneak in after the installation process scans for and/or eliminates any viruses. Given the way certain types of malware (eg: rootkits) hook an OS at an extremely low-level, I think it takes a reboot to assure successful eradication.