Dr Andrew C Aitchison wrote:
> What do other groups do about updating applications and machines
> with long running processes ?
> 
> My users run two sorts of long running processes, with different
> problems when it comes to updates.
> 
> First, I have users who never log off. Thus applications like
> firefox and pdf viewers will be running when they are updated.
> Some time later these applications may try to load and run plugins
> which have been removed/updated.

I never logoff, and rarely reboot anything between power failures. In my 
usage (home, small office), I've never felt the need to update to the 
latest kernel just because it's there. I did feel the need last year 
when CentOS4 (and RHEL I think) had a series of kernels that locked up 
after some time on my hardware.

Applying updates and keeping on using the system has never caused a 
problem that I've noticed, open shared libraries and such are not 
actually deleted until every process has closed them. New versions of 
applications get the updated libraries.

Given "binary compatibility" I don't anticipate a problem, except when 
there are major updates such as firefox 1,5 to 2.0 or to 3.0.

If an application crashes, I just restart it.

> 
> Second, I have users with long running calculations (often weeks
> or more) which would be interrupted if the machine were rebooted into an 
> updated kernel. User-writing code often check-points, so the actual 
> calculation time lost is not significant, but calculations in
> commercial packages such as Mathematica and Maple are often less good 
> about check-pointing.

Then don't updated them until there is a time available to do so. 
Presumably, they're sensibly firewalled and otherwise protected from the 
ungodly?



> 
> How do people balance the disruption of killing user processes
> against the need to update to the latest versions of software ?

Updating software is to prevent a problem you might have. In your case, 
updating software is more likely to cause grief than prevent it. I'd not 
update until I could take the system out of service. After updating, 
your systems might need some QA to ascertain they're still fit for service.




-- 

Cheers
John

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