Re: Config-mgmt Digest, Vol 32, Issue 2

On 2 Oct 2008, at 20:00, John Rouillard <rouilj@...> wrote:

> I am not claiming that a file is the ultimate end all, but it does
> provide a level of granularity that can be measured.

I guess I'm just not sure what you are measuring by doing this  
though ...
It doesn't really relate to the effort required to make the change,  
or the potential
disruption, or .... (anything useful?)

>> Who cares how
>> many low-level operations (file replacements, file edits, database
>> inserts, process restarts) the configuration management system needs
>> to perform?
>
> Well the goal is to get a configuration change deployed. If you are
> waiting for an hour for the CM system to run through it's file
> generation, update, restart to impose a configuration then it is a big
> deal as it contributes to waiting time which is a type of waste under
> a LEAN framework.

Um. I'm still don't get this. Isn't it like saying that you are going  
to write
raw machine code because you can't be bothered to wait for the
compiler .. .. ? Usually, having it correct is more important than fast.

> Then you may have to do it a couple of times if you didn't get the
> config right the first time. Right now depending on how well the
> operator uses DACS, it can range from 30 seconds to 7 minute wait for
> getting a set of files deployed. Now because DACS is a push system and
> not a pull system, the user can see the delay directly. In a pull
> system I get the impression that people are sort of used to waiting
> for a config change to propigate. Comments from the bcfg2, puppet,
> cfengine, LCFG authors?

LCFG does "poke and pull" which probably the most efficient. When a  
change is made,
the compiler pokes the client which pulls the file. If the client is  
offline, it just polls next
time it comes back, so the server doesn't block. If the client is  
online, it gets the
update immediately.

The "compilation" can take along time though. Some core
change which affects all of 1000+ machines can take over 30mins. This
really only bites when someone has made a mistake and needs to send
out an urgent fix!

   Paul

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