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Re: setting runlevel to single-user
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: Re: setting runlevel to single-user
- From: Ben Goren <ben_(_at_)_trumpetpower_(_dot_)_com>
- Date: Thu, 28 Oct 2004 09:06:51 -0700
On 2004 Oct 28, at 4:54 AM, Brett Lymn wrote:
> It's interesting that you get a lot of people in the open source world
> with the "little network" view, scalability and managability are just
> not cool concepts and hence are deemed "too hard/complex".
Humor me. Please describe one of these uber-complex systems with lots
of complex startup scripts and interdependencies that can't be handled
by a simple rc script and rc.conf.
I've tried to imagine scenarios, and I keep coming up with horrendous
kluges that either address problems that don't or shouldn't exist or
are using the wrong tool to solve the wrong problem.
For example, I could imagine an IMAP server that depended on an
authentication agent that depended on a database. Your first thought is
that you'd need to start them all in the proper order. But, if that's
the case...what happens when one of the program dies or you have to
restart it? Do you have to bring all of them down and then bring all of
them back up again? If that's the case, I'd say something's broken.
The programs that depend on each other should gracefully deal with the
absence of the other programs. In my scenario, if the authentication
agent is down, the IMAP server should either refuse logins with an
informative message until things are back to normal, or try to start
the authentication server itself. If neither are possible, you need
some sort of a watchdog--and a better IMAP server. You might also need
a watchdog to alert you when one of the programs dies.
But none of that has anything to do with the boot process. If you start
the IMAP server too early in the boot process, then somebody who tries
to check mail in those ten seconds before the authentication agent
starts will get an error message or will have to wait an extra ten
seconds for the agent to start up. This is a problem...how?
And, even in a worst-case scenario, just put the stanza for the
authentication agent between the stanzas for your database and IMAP
server. If they're really that sensitive, put them together in a block
with a comment saying why they're that way. If you're also running a
Web server and a DHCP server and an FTP server and Samba and VNC and a
Foo server, what matter if they get started before or after your IMAP
server? They don't care.
So, again...what's the problem, and why do you need complex init
scripts to solve it?
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