[Oneiric-Topic] Server Boot

Clint Byrum clint at ubuntu.com
Thu Apr 7 06:13:27 UTC 2011


Excerpts from Sander Smeenk's message of Wed Apr 06 12:25:55 -0700 2011:
> Quoting Clint Byrum (clint at ubuntu.com):
> 
> > >  * GRUB's default "graphical console"
> > Not sure I follow you .. whats the problem here? It looks pretty "texty"
> > to me, but I have been primarily booting it in VM's.
> 
> GRUB, Plymouth and later console-setup fiddle with the 'VESA Video
> Mode'(?) of the text console. GRUB does it to display backgroundimages,
> Plymouth for the splashscreen and console-setup changes the font of the
> consoles.
> 
> The problem is that lots of *LOM, *RMC and DRAC solutions completely
> choke on these "nonstandard" videomodes. I could blame that on the
> crappy Java applets they use, ofcourse. But why?! ;)

There are actually a lot of good things about using higher video modes on
servers. The added width and lines in the console mean less information
is lost when switching VT's for one.

It might make sense to restrict the video modes if one of these devices
is found.

> 
> > >  * Plymouth splashscreens (even textbased ones!)
> > With things starting in parallel, plymouth is just a multiplexer that
> > keeps messages and user interaction from running all over eachother.
> > I'm not sure why you'd be against that.
> 
> I'd be happy with unsorted lines prefixed with a PID or procname or
> something. It would be like going through maillogs, i'm used to that ;)
> 

Thats close to what you will have in 11.04 and later. The point is that
sometimes we need to query the user, like if Apache has an encrypted SSL
cert or there are encrypted volumes. Without Plymouth, the parallel stuff
going on in the background would just stomp all over the prompts/answers.

> Current(!) Plymouth, in Lucid and Maverick at least, obstructs me in my
> work with >300 servers running Ubuntu Server.
> 
> Real-life examples: i can't see why or rather when my server
> spontaneously rebooted, or what that kernel panic was i could identify
> by the keyboard-leds, but nothing was on my screen.
> 
> I have had servers show the bootscreen with red/white dots, aparently
> stuck, no messages on screen but hitting 's' made it boot (nobootwait
> issue). All these things really stress me out when i'm trying to quickly
> fix a problem with a server. And one question remains: why? ;)

The "press S to continue" thing confuses a lot of people.

The thing I can say is, in future releases you won't just get dots and
the question. I do think there's an open bug suggesting that this also
have a timeout so the boot can boot and have sshd up if possible so
the FS can be fixed remotely.

> 
> > Agreed that some things have been done to the boot that make no sense
> > for servers. You've done a nice job identifying a few of them above.
> 
> Yeah. You've nailed my point. "Ubuntu" is geared, or gearing, towards
> Desktop users. I have no beef with that, i love Ubuntu on the desktop.
> My parents love it too. It just works so well.
> 
> When i install Ubuntu on a server i keep asking: why?
> Why do we want our server to have backgrounds in GRUB and show
> bootscreens during boot? Why do we want to start processes in parallel?
> With current hardware it takes longer to get through all BIOS POSTs,
> disk-detection, PXE and other ROMs than it takes to boot the OS. ;)

There's definitely a move toward more virtualization and separation,
where the parallelism is an asset. Even on a big server, having the
ability to make services reactive to events *other* than 'runlevel'
can be quite useful.

I do think we need to do a better job of isolating things and defining
the state of the system that services require before they can start.
Once that is done, I hope you and other users will not even notice the
parallelism other than the order of events occasionally changing slightly.

> 
> One solution could be a subset of packages geared to servers?
> Don't know how feasible that is. 
> 
> Currently it's really only the kernel that makes a server install a
> server install. The packages installed are all the same available on the
> desktop. There's just less pulled in though metapackages at install.
> 

There's also the plymouth theme that is different on the server. And
don't forget that servers are supported on LTS for 5 years instead of
just 3 for desktops.

What packages should we do differently for the server?




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