[CentOS] CentOS and typical usage

Sun Dec 13 16:09:51 UTC 2015
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On Sun, December 13, 2015 8:51 am, Alice Wonder wrote:
> On 12/13/2015 04:19 AM, Timothy Murphy wrote:
>> Alice Wonder wrote:
>>> In the server environment you almost certainly are using a virtual
>>> machine, and to use a virtual machine you create an image. Set up the
>>> image how you want and be done with it, you can then deploy it
>>> thousands
>>> of times and it is set up the way you need it.
>> Who is "you"?
>> I'm running a home server under CentOS-7,
>> and I'm not using a virtual machine.
>> Why should I?
>> I don't want to "deploy it thousands of times".
> You is an author's you, kind of like author's we. I understand author's
> you and we are going out of style, but they are very much ingrained
> within me.
> I mean the typical server and indicated a server environment opposed to
> a home environment.

I'm joining my "you" to yours. I'm even joining the kind of what one often
does for servers: virtualized stuff, even though my case is FreeBSD jails
(mostly even more comparmentalized than single virtual machine: one jail
per service or per group of services which need to talk to each other
through UNIX sockets; still I put mu case in the same category with

>> It's amazing how people assume that everyone in the world
>> is, or should be, running things in the same way as themselves.
>>> I was one of the systemd haters initially but now I don't have an issue
>>> with it. Yes it is different than what I learned,
>> I dislike systemd because it is much more complicated than its
>> predecessor,
>> and it has no advantages in my case to make up for this.
>> The main advantage that was originally claimed was that it boots faster.
>> That is not the case on my Fedora laptop.
>> It is no faster, and it is much harder to work out what is happening
>> if something goes wrong.
> It's not speed that matters to me, and I would be fine with System V
> init. However it seemed at the end of the day, most of the arguments
> against systemd boiled down to "we've never done it that way before" or
> "It's not the UNIX way" rather than actual technical reasons why System
> V should be used and systemd rejected.

true. Pretty much as true would be: why should we (*nix admins) be like
certified Windows admins: every incarnation of the system we have to learn
new way to find yet the same on the low level code tools. I know systemd
is not it, it is quite different architecture. But jumping to this
incarnation of Linux does feel similar.

> One of the benefits of systemd is the dependency based parallel startup.
> The same speed can often be achieved with system V init by fine tuning
> when the services start but systemd does that automatically.
> Speed though doesn't concern me. I almost never reboot my servers or my
> desktop or laptop (I do sleep the laptop but only reboot after kernel
> update)

Well, for last 6+ years you should: at lest once every 45 days on average
(either kernel or glibc security update, - just my observation). Of
course, time the machine boot takes doesn't by any measure compare to
interval between reboots. Neither it does compare to the fact you have to
reboot the server. The funniest thing is: for some of the server hardware
initialization by BIOS, which has to happen even before system boot
starts, takes longer than system V init (not talking about faster systemd
boot as I only can compare with workstation systemd boot: I do not have
servers running systemd based system). So all in all the best pro systemd
argument - fast boot - kind of doesn't exist for me. I know, tastes
differ. But if I _have_ to reboot server often, it is time to build
service cluster in which case reboot of single machine doesn't matter.
Neither the time the it takes to boot matters, so we are back to square
one: no advantage of systemd's fast boot (just IMHO).


> Especially with SSDs, boot time isn't an argument for systemd - and I do
> not want to convince anyone that it is better. Just that it is not
> difficult to use, there are some advantages - how valuable those
> advantages are depend upon what you do (author's you again, not personal
> you) but it seems that these advantages have since been seen by just
> about every Linux distro that has any significant market share.
> Popular doesn't make it right, but it did make me rethink my objections
> to it and whether or not those objections were rational. For me, I
> decided that no, they weren't rational.
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos

Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247