[Fedora-directory-users] lagest depoyment?

Mike Jackson mj at sci.fi
Tue Nov 15 05:14:20 UTC 2005


speedy zinc wrote:

> They were laughing at what we call "software
> engineering",
> because they can easily prove at what load their
> bridge
> will crash, but I have no way to prove at what load my
> server will crash.

No, they can not easily prove what the straw that will break the camel's 
back is. They can only prove mathematical cases which would never happen 
in real life. For example, they might say that if you put a 500,000kg 
weight which occupies one square meter on the center of this bridge, 
then it will certainly break. They have no way of knowing how many 
cars/trucks the bridge can really hold before it breaks, because the 
cars will be spread at different distances, will weigh differently, 
travelling at different speeds, etc. They do not conduct those type of 
bridge system performance tests in real life to see where the bridge 
really breaks, because they don't really want to break a bridge to find 
out (too costly, plus it would kill people and destroy a lot of cars). 
Therefore, we live with conservative capacity statements (estimates) 
from bridge engineers, which are derived from abstract mathematical 
cases and/or computer simulations.

Computers have many variables which can be tuned for different purposes, 
so the absolute performance is difficult to abstractly state.

I suggest you take some time to study system performance testing. 
Another thing worth understanding is the difference between software 
engineering and system engineering.

Finally, I can't give you details about my deployments because it would 
reveal sales related numbers of the system which I work with - something 
which I am not allowed to reveal because of business reasons.

--
mike




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