Re: [gentoo-user] Re: Managing multiple Gentoo systems

[Joshua Murphy <poisonbl@gmail.com>]

On Tue, Jul 12, 2011 at 2:23 PM, Grant <emailgrant@gmail.com> wrote:
>>>> Have you considered using PXE to network boot your systems? you can
>>>> have various configurations set up based on mac addresses to address
>>>> different hardware issues. I recommend trying out SystemRescueCD to
>>>> experiment with PXE booting for the client and server.
>>>
>>> That sounds like exactly what I need.  So, I could set up a Gentoo
>>> server and a bunch of completely diskless clients which would all PXE
>>> boot from the server?  Would the clients basically each control a
>>> different virtual terminal on the server?
>>
>> Each machine can pull a copy of the master boot image to make updates
>> a lot simpler. The SystemRescueCD PXE boot mechanism just pushes out a
>> copy of the CD to all the machines to boot them. to update the boot
>> image just update the files in one location to update all machines.
>> the machines act as separate fully functioning machine. Check out
>> http://www.sysresccd.org/Sysresccd-manual-en_PXE_network_booting to
>> see how to setup the PXE boot environment.
>
> I think I get it now and it sounds great, exactly what I'm looking for.
>
> Everything can be done in RAM, no disks required?
>
> Can PXE boot be done wirelessly?  Maybe only if the wireless is
> onboard?  I tried to Google this but the info returned is terribly
> outdated for some reason.
>
> Do you think SystemRescueCD is the best boot image for clients that
> only need a browser?
>
> What sort of machine would work well as a client?  Should I just put
> together a bunch of motherboards with onboard video and ethernet,
> CPUs, RAM, PSUs, and small cases?  Is there a prebuilt system that
> works well for this?  Maybe an ARM-15 system as "Tampa Bay" James
> referenced, although I think that isn't released yet.
>
> - Grant

Well, the first thing you need to decide is whether you want each
client running that browser locally, or whether you want each client
to merely provide an interface to the server, and every user's browser
(and every other application) running on the server itself. If your
clients boot, then run all their own software locally, your server's
under only under load during boot-time and your clients need to be
able to handle that work (not much, but it's more than nothing, just
try running a modern Firefox on 64MB of ram). On the other hand, if
your clients merely boot into a remote connection to the server, a la
VNC or NX, the client does *very* little locally, can run on next to
nothing hardware-wise (a true 'thin client'), and the entirety of the
workload is offloaded to the server. If you want responsive 'eye
candy', 3D graphics work/play, or any form of particularly 'smooth'
animation, you will want that work to be handled on hardware closer to
the user (requiring a far faster processor, more ram, a capable video
device, and likely local storage for swap at the least), while serving
up a simple browser to the user is far more forgiving.

As for wired vs wireless, true hardware PXE booting is generally
limited to wired scenarios, but it would be entirely possible (though
not truly 'diskless') to deploy a minimal kernel+initramfs that
handles initial booting, joining WiFi, pulling down of the system
'image' from your server, and handing control off to that in the same
way your run of the mill kernel+initramfs loads hardware drivers until
it can find the harddrive, attaches to the root partition, and hands
off control to init from there. Changes to the wireless configuration
would require directly visiting each client, and client-side kernel or
initramfs updates easily could as well, if things don't go as planned
(but, since all the user-side software is either run on the server or
loaded from it at boot-time, changes to the client's "loader"
shouldn't be frequent).

There's also the option of pre-made hardware thin clients that
typically boot from internal flash and simply provide a remote
interface to a central server (though most are geared towards RDP or
Citrix), and some are even WiFi capable.

-- 
Poison [BLX]
Joshua M. Murphy