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

Corey Minyard cminyard at mvista.com
Mon Mar 28 08:54:03 PST 2005


Brian F. G. Bidulock wrote:

>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.
>  
>
I do.  Nortel switches work this way, for instance.

>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.
>  
>
I don't think RPM really becomes involved here.  I guess you could use 
RPM to manage patches being installed, but it doesn't seem suitable and 
I doubt smaller systems in the field have RPM databases.

Patching is also helpful for things like radios, line cards, and other 
smaller and simplex things in the system.

-Corey

>--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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>>    
>>
>
>
>  
>




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