[CentOS] Cemtos 7 : Systemd alternatives ?
Lamar Owen
lowen at pari.edu
Tue Jul 8 15:58:45 UTC 2014
On 07/08/2014 11:37 AM, Always Learning wrote:
> Please see the link above. I used it to find the 'stateless' item, and
> after selecting it clicked on
>
> http://0pointer.de/blog/projects/stateless.html
There are many use cases involving servers where such a capability would
be highly desirable. Most are cloud-oriented, where you want to spin up
an instance rapidly (to deal with increased load, perhaps) and then spin
it down, and having dynamically loaded /etc and /var content allows this
in a smooth manner. Static servers have their uses, of course, but at
least in my data center I find actual server load to be very dynamic,
but power load to be rather static; why *shouldn't* the power used be
proportional to the work load?
The real promise of 'cloud' technology is for us in in-house servers
that can spin up only when needed, saving power and cooling costs in the
process. Stateless is not the only way to go, of course, and nothing in
the blog post to which you link is 'never again honor anything in /etc
and /var' to be found, but rather, much like /etc serves as a fall-back
for many programs who look first in a dot-file in ~, the content in /usr
serves as an OS-default fallback to the per-system (or per-instance)
configuration and state in /etc and /var.
It is a different way of looking at things, for sure, but I can
definitely see a server use-case for this sort of thing, especially
since there is significant budget pressure to reduce power costs.
And dynamic spinup of servers to handle increased load is a use case for
systemd's rapid bootup. They go hand-in-hand.
The Unix philosophy unfortunately sometimes misses the forest for all of
the trees. Sometimes tools need to actually be designed to work
together, and sometimes a Swiss Army Knife is the right thing to have.
(And I'm an old Unix hack, too, having used Unix of several flavors
since before Linux was even a gleam in Linus' eyes).
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