an OS question

[cellio]

While waiting for assorted software updates to install today I found myself wondering... Mac OS and Windows usually need to reboot your machine to install updates. Yet I have, several times, seen Unix machines that I believe were being maintained with uptimes of more than a year. What's the deal? Is Unix just better able to support hot-fixes, or are Unix updates that rare? (Or am I wrong about the maintenance of those machines?) And if it's that Unix is better at updating, why does Mac OS, which is Unix-based, need to reboot so often? Mind, it's definitely better in this regard than when I was running Windows; this is a puzzle, not a rant.

Edit: Thanks for the comments thus far. I now understand more about how Unix is put together, and why Windows is different. Still not sure about Mac OS but comments suggest it could be UI-related (that is, the GUI might be more tied into the OS than is the case on Unix).

Comments

[dragonazure.livejournal.com]

Its been a long time since I did any operating systems work, but from what I remember, it largely depends on the type of update. In UNIX, I haven't seen/been involved in a major upgrade in ages, but usually, only services and device drivers get updated and that doesn't require restarting the entire system--just "refreshing" the services. A serious upgrade to the OS kernel will generally require restarting the system. If you have to have to reconfigure your system settings, that also usually requires a restart of the system, but I don't think that is what you are asking....

With Windows, I suspect that certain things are still very closely coupled to the operating system kernel. If I were a little more paranoid/cynical, I might think it is also a sneaky way to mask memory leaks and garbage collection problems.... 8^) To be honest, I do get a lot of Windows "hot-fixes" at work, but I suspect they simply are patches and upgrades to non-core components of the system (or what passses for TSRs these days)

[cellio]

I get lots of updates at work too (where I am currently using XP), but I usually can't tell which are OS upgrades and which are application-level stuff that our IT department has decided we need. We just get a generic message about updates (and instructions to reboot).