[cgl_discussion] Re: [cgl_specs] Use case - Live patching

[Brian F. G. Bidulock]

Timothy,

We would stop one of the redundant processors, patch it, and then
bring it back up and switch over from the online side.  A bounce
in the middle could be problematic but that is usually true of all
planned outages.  I don't know of any telco switches that actually
continue running call processing on the same processor that is being
patched.

More related is the telco requirement for version conversion and rollback.
Once the offline side is patched and the database updated, the online side
(unpatched) must be able to run against the new database.

Rpm does not accomplish this latter requirement.

--brian


On Mon, 28 Mar 2005, Timothy D. Witham wrote:

> On Mon, 2005-03-28 at 09:05 -0600, Corey Minyard wrote:
> > Why do you think it is evil?  It is standard practice in most large 
> > telecom systems as it improves availability.
> > 
>     Maybe it would be better to word it as "it can improve
> availability". 
> But it really is a hold over from the single large expensive CPU design
> days.
> 
>     If you don't exercise absolute top down control you get to a
> situation
> were there isn't a correlation between what is on the disk for a reboot
> and what is in memory being executed.   While a phone company
> might be able to control their switch with rather infrequent updates
> in the general usage this can cause real issues. 
> 
>  In fact from my support of phone company days I remember a 
> couple of issues where switches where bounced because of a 
> major environmental issue and when they came back up they
> were missing features and patches.  They were in such a sorry
> state that they had to be reloaded in order to function correctly.   
>  
>     Tim
> 

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