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Re: I'm not a huge fan of systemd



On Fri, Jul 18, 2014 at 6:22 PM, Steve Litt <slitt@troubleshooters.com> wrote:
> On Fri, 18 Jul 2014 18:29:23 +0200 Sven Joachim <svenjoac@gmx.de> wrote:
>> On 2014-07-18 17:21 +0200, Steve Litt wrote:
>>
>>> The other thing is, a lot of people thought the current init system
>>> was working just fine.
>>
>> They should read the mail[1] by one of its maintainers which states
>> that it was (and is) _not_ "working just fine", and that a
>> replacement has long been overdue.
>
> I've used Linux every day since March 2001, and I never had a problem
> with the way it booted or initialized, other than Grub2. Until this
> systemd thing came up, I never heard an *actual Linux user* gripe about
> its init, although of course the pro-Microsoft and pro-Apple folks
> griped about it all the time.
>
> Some guy writing an email about all the theoretical flaws in a product
> doesn't make the product flawed for the millions who boot their
> computers with it everyday, and never give it another thought. The few
> who really have a problem with the way Linux inits up could have been
> given upstart or systemd or, for that matter, daemontools as an
> alternative, without affecting the vast majority who saw absolutely no
> problem with the way it had been done.
>
> And finally, note that the guy's email doesn't specifically recommend
> systemd, and as a matter of fact seems to gravitate toward upstart,
> which has a long history of doing the right thing and is known by many.
> And although his email doesn't talk about user space *applications*
> getting entangled the init system, I have a feeling he wasn't
> envisioning rank and file applications requiring parts of the init
> system.

You must've missed the part where Sven mentioned that this "some guy"
is the maintainer of sysvinit in Debian. He's also the upstream
maintainer of sysvinit.

I think that I've posted this link in the past:

https://lists.debian.org/debian-devel/2012/02/msg01043.html

This is the text of the email:

--%<------------
> Currently we have a system where every user has a chance to debug
> and fix those problems and make their system work again.

I just wanted to give a small comment on this, as one of the sysvinit
package maintainers in Debian. The quoted text give the impression
that the current init.d based boot system is working fine, and that is
not quite how I see it.

The current sysvinit boot system is not working properly on Linux. And
it has broken in new and interesting ways the last few years, thanks
to the fact that the linux kernel developers have removed the big
kernel lock, causing the kernel to become more event based and less
sequential during boot.

These problems lead to boot failures when some kind of hardware is
used (think disks and network cards, but it can happen with any
hardware), because it is not possible for the current dependency based
boot system to know when some hardware device is available during
boot. A well known case is having the user home directory on an
external USB disk, only to discover that the disk device node isn't
available when file systems are mounted during boot. There are other
examples.

To solve this problem the early boot (note only the early boot _need_
this) need to become event based, and once the file systems, network
interfaces etc are set up, the later boot can work using simple init.d
script dependencies.

I do not know the proper solution to this for Debian, but both upstart
and systemd seem to provide a working solution with different costs
and advantages.

-->%------------

If he didn't improve sysvinit to deal with the early boot problem that
he identifies here, he must've either thought that it wasn't possible
to fix the sysvinit code or that he didn't have the time to dedicate
to doing so.


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