[Lxc-users] Many containers and too many open files

[Brian K. White]

On 2/25/2011 2:06 PM, Geordy Korte wrote:
> Maybee a really stupid question... but why would you want to run that many containers?

I won't say it's stupid but I'll say it's meaningless. Don't take it as 
an insult I'm just explaining it's the wrong way to think about it.

It's like asking why do you need 10 computers or 3 cars or 17 pairs of 
pants or an infinite number of integers in math? What would anyone do 
with those really big numbers higher than say, 1 billion?

The answer is really, since a container is essentially like any other 
computer, a general purpose tool, you don't have any specific number of 
them that you need. Anyone might need any number of them for any reason. 
And you generally need more and more of them forever for all manner of 
different uses.

So what you want to know is simply what are the limits? Most people 
probably don't have any specific magic number that must be met, we just 
need to know where are the various limits, whether that turns out to be 
20 containers per host or a million.

Also there is the fact that, many times the indisputably valuable "real 
world" uses for things only come about _after_ they have been made 
possible. People thought the invention of the transistor was a pointless 
curiosity at first.

If 1000 (or more) containers is possible, then before long I guarantee 
you someone will invent some non-trivial use for that capability.

And that's not counting the obvious ones we can already think of right 
off the top of our heads like:
- A service provider being able to run all their customers web sites, or 
as in my case their core back office industry-specific custom software, 
on a single or few machines instead of 1500 machines.
- Running stress tests like simulating 1500 users or network nodes 
hitting a single service or interacting with each other mesh-like, by 
having 1500 vm's actually do it, instead of the old way of either being 
rich and having a bunch of real machines, or "deploy and hope".
- Developing and testing tools that manage lots of servers, without 
having to actually have a lot of real servers sitting there idle just 
for that. When I make some new script to do something like run a command 
or modify a config file on all of my production servers at once, I 
_really_ would like to test that on a 1500 vm's instead of the real 
production boxes.

-- 
bkw