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-   -   Simpler method for fat/thin client setups (http://www.linux-archive.org/edubuntu-user/651588-simpler-method-fat-thin-client-setups.html)

Alkis Georgopoulos 04-02-2012 05:58 AM

Simpler method for fat/thin client setups
 
Now that the ltsp-server and ltsp-client packages are allowed to be
installed simultaneously (LP: #950945), I thought of an extremely simple
method to install and maintain LTSP fat/thin computer labs that should
be appealing to certain setups like small school labs.
We'll probably start using it in Greek schools in a month, and I'd like
to ask the community for feedback on where this could lead to problems,
and also on whether there's interest in an internationalized version of
the "ltsp-server-pnp" package that we'll develop to automate this.


The installation steps for this new method will be:
1. Install your server normally with any DE you prefer (Gnome, KDE,
XFCE, LXDE...). Also install and configure on the server any
applications that you want to have in your thin/fat clients.
2. Add the repository for the yet-to-be-developed ltsp-server-pnp
package, which automatically installs and configures ltsp-server,
ltsp-client, dnsmasq, PXE menus etc for you.
3. Reboot your server and select "Recovery console" in the grub menu.
From the recovery menu that will appear, select "Generate LTSP image".
This will create the /opt/ltsp/images/i386.img NBD image, and it will
need about 5-10 minutes to complete, without requiring Internet
connectivity.


That's all, you can then boot your server normally and start your
thin/fat clients. If you need to "update your chroot" in the future, you
just do any changes you want directly on the server (add/remove apps or
settings) and follow step (3) again.


Pros:
* Great simplicity. As you've seen, there's *no LTSP chroot
involved*, so no "ltsp-build-client" step, no "ltsp-chroot install
packages" step, no "manually transfer gconf mandatory settings to the
chroot" step.


Cons:
* Loss of flexibility. The server needs to be the same arch as the
clients, so you'll probably want the i386-pae kernel in your server. You
can't even have different packages installed in your server than in your
thin/fat clients. But you can still have e.g. apache, mysql, sshd etc
installed on your server and put them in the RM_SYSTEM_SERVICES lts.conf
directive so that they don't run in your clients. No, that doesn't put
any additional RAM overhead, your clients can still have as low as 128
MB RAM no matter how many services you have installed on your server.
And of course in bigger setups you can use a separate server for
NFS/apache/whatever, and only keep the LTSP-related services in the
server where ltsp-server-pnp runs.
* Security concerns. E.g. the clients will have the same sshd keys as
your server. But I think that in step (3) above, the security-sensitive
data can be regenerated or omitted. And of course /home, /srv, /opt, and
user's entries in /etc/passwd and /etc/shadow will be omitted too in the
NBD image.
* Finally, your server needs to be rebooted to update the NBD image,
so some downtime is involved. This will be avoided in the future when
BTRFS snapshots will be available.


Thoughts? And, does anyone care about an internationalized Ubuntu
Precise/Debian Wheezy package for this?


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David Groos 04-02-2012 03:11 PM

Simpler method for fat/thin client setups
 
Personally, while I've grown to enjoy the command line, I would suffer little sense of loss at no longer needing to use it in chroot development and maintenance. I like the idea that, as you set up and develop the capabilities of the server one is simultaneously accomplishing the same with the thin/fat client--very efficient and transparent.

The need to reboot the server into grub recovery mode is a limitation for my implementation. I manage the edubuntu servers remotely and in one case it is not physically accessible. Therefore I use terminal with ssh but even more use OpenNX to access the server. Sounds like everything would work great here except I don't see how I could do the grub screen step since this screen is not available to OpenNX--though is it via ssh? Do you see a work-around? Sounds like BTRFS snapshots will solve this but not sure of its timeline. Although with the lower server needs with the fatclient technology, I may be moving to having each classroom use a good desktop (the teachers) as the server and no longer use a full-blown server in a tech closet. Nice to have options.

At the end of the summer/before the start of the school year I set up one 'golden server' then using clonezilla, clone that image to the other servers only needing to adjust a few network config files. How would this new system impact how I have been propagating the server?

It seems you are saying that I could get LDAP authentication, Apache caching/filtering working on the server and then not have them running on the clients--is this like the opposite of localapps? Would I have to specify each application I don't want to run locally? I may need some guidance here.

Let me know how I can support the internationalization or testing of this: it is continuing to move Ubuntu/LTSP in a highly practical direction. This will help me in my push to get Ubuntu/Edubuntu more into the mainstream of our school district--whenever you lower the entrance bar for a technology you make it a more welcoming, more accessible option. Thanks for your continued efforts, Alkis.

Looking forward to seeing others' responses.

David G

On Apr 2, 2012, at 12:58 AM, Alkis Georgopoulos wrote:

> Now that the ltsp-server and ltsp-client packages are allowed to be installed simultaneously (LP: #950945), I thought of an extremely simple method to install and maintain LTSP fat/thin computer labs that should be appealing to certain setups like small school labs.
> We'll probably start using it in Greek schools in a month, and I'd like to ask the community for feedback on where this could lead to problems, and also on whether there's interest in an internationalized version of the "ltsp-server-pnp" package that we'll develop to automate this.
>
> The installation steps for this new method will be:
> 1. Install your server normally with any DE you prefer (Gnome, KDE, XFCE, LXDE...). Also install and configure on the server any applications that you want to have in your thin/fat clients.
> 2. Add the repository for the yet-to-be-developed ltsp-server-pnp package, which automatically installs and configures ltsp-server, ltsp-client, dnsmasq, PXE menus etc for you.
> 3. Reboot your server and select "Recovery console" in the grub menu. From the recovery menu that will appear, select "Generate LTSP image". This will create the /opt/ltsp/images/i386.img NBD image, and it will need about 5-10 minutes to complete, without requiring Internet connectivity.
>
> That's all, you can then boot your server normally and start your thin/fat clients. If you need to "update your chroot" in the future, you just do any changes you want directly on the server (add/remove apps or settings) and follow step (3) again.
>
> Pros:
> * Great simplicity. As you've seen, there's *no LTSP chroot involved*, so no "ltsp-build-client" step, no "ltsp-chroot install packages" step, no "manually transfer gconf mandatory settings to the chroot" step.
>
> Cons:
> * Loss of flexibility. The server needs to be the same arch as the clients, so you'll probably want the i386-pae kernel in your server. You can't even have different packages installed in your server than in your thin/fat clients. But you can still have e.g. apache, mysql, sshd etc installed on your server and put them in the RM_SYSTEM_SERVICES lts.conf directive so that they don't run in your clients. No, that doesn't put any additional RAM overhead, your clients can still have as low as 128 MB RAM no matter how many services you have installed on your server. And of course in bigger setups you can use a separate server for NFS/apache/whatever, and only keep the LTSP-related services in the server where ltsp-server-pnp runs.
> * Security concerns. E.g. the clients will have the same sshd keys as your server. But I think that in step (3) above, the security-sensitive data can be regenerated or omitted. And of course /home, /srv, /opt, and user's entries in /etc/passwd and /etc/shadow will be omitted too in the NBD image.
> * Finally, your server needs to be rebooted to update the NBD image, so some downtime is involved. This will be avoided in the future when BTRFS snapshots will be available.
>
> Thoughts? And, does anyone care about an internationalized Ubuntu Precise/Debian Wheezy package for this?
>
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Alkis Georgopoulos 04-02-2012 04:20 PM

Simpler method for fat/thin client setups
 
Στις 02/04/2012 06:11 μμ, ο/η David Groos *γραψε:

The need to reboot the server into grub recovery mode

> is a limitation for my implementation.

How about "sudo grub-reboot ltsp-pnp-grub-entry" then?
That would reboot your server, automatically select a related grub menu,
generate the squashfs image, and continue with the boot process after
it's done.



> At the end of the summer/before the start of the school year
> I set up one 'golden server' then using clonezilla, clone
> that image to the other servers only needing to adjust
> a few network config files. How would this new system
> impact how I have been propagating the server?

You could still do the same, no difference there.
Or since the same image now contains both the server and the client
functionality, you could netboot your other servers from the golden
server, but it's too soon to go into details about that idea. :)



> It seems you are saying that I could get LDAP authentication, Apache
> caching/filtering working on the server and then not have them
> running on the clients--is this like the opposite of localapps?
> Would I have to specify each application I don't want to run
> locally? I may need some guidance here.

Why disable LDAP on the clients? LDM would still use ssh for authentication.
For apache, sure, you could set RM_SYSTEM_SERVICES=apache2 in lts.conf,
or you could have it running on a server that's not part of your LTSP
setup. That server could e.g. host NFS, LDAP and apache, and your other
servers would be your NBD+application servers.


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Alkis Georgopoulos 04-09-2012 06:36 PM

Simpler method for fat/thin client setups
 
A first release of ltsp-pnp is available, for more details see:
https://help.ubuntu.com/community/UbuntuLTSP/ltsp-pnp

Warning, don't use it on production machines, it's beta-quality yet.

In a test I made, I installed Ubuntu 12.04, then ltsp-pnp, and ran
ltsp-publish-image. In 10 minutes the compression finished and an 1.5
Gb /opt/ltsp/images/pnp.img was generated with about the same contents
as my server, and I was able to boot thin and fat clients with it.

No server reboot was necessary (apt locking was implemented).

A screenshot with the PXELinux menu automatically generated by ltsp-pnp
(I deliberately had a very complex setup):
http://imagebin.org/index.php?mode=image&id=207317

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Alkis Georgopoulos 05-29-2012 01:52 PM

Simpler method for fat/thin client setups
 
The ltsp-pnp method of maintaining LTSP installations without a
chroot is now upstream in LTSP.

It's no longer a separate package; all that's needed is to run
ltsp-update-image --cleanup /

and that will generate an /opt/ltsp/images/i386.img image out
of the server disk contents, while excluding sensitive data like
user accounts and ssh keys.

The newer LTSP version required is currently available for Ubuntu
12.04 from a PPA and it should be available later on for Debian
Wheezy as well.

More info: https://help.ubuntu.com/community/UbuntuLTSP/ltsp-pnp

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Dean Mumby 05-30-2012 11:29 AM

Simpler method for fat/thin client setups
 
Thanks for link , have followed instructions as per page on fresh install

1. the ltsp-config lts.conf command kicked out an error that the sample file could not be found.



----- Original Message -----
From: "Alkis Georgopoulos" <alkisg@gmail.com>
To: ltsp-discuss@lists.sourceforge.net
Cc: edubuntu-users@lists.ubuntu.com
Sent: Tuesday, 29 May, 2012 3:52:24 PM
Subject: Re: Simpler method for fat/thin client setups

The ltsp-pnp method of maintaining LTSP installations without a
chroot is now upstream in LTSP.

It's no longer a separate package; all that's needed is to run
ltsp-update-image --cleanup /

and that will generate an /opt/ltsp/images/i386.img image out
of the server disk contents, while excluding sensitive data like
user accounts and ssh keys.

The newer LTSP version required is currently available for Ubuntu
12.04 from a PPA and it should be available later on for Debian
Wheezy as well.

More info: https://help.ubuntu.com/community/UbuntuLTSP/ltsp-pnp

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Alkis Georgopoulos 05-30-2012 02:43 PM

Simpler method for fat/thin client setups
 
Στις 30/05/2012 02:29 μμ, ο/η Dean Mumby *γραψε:

Thanks for link , have followed instructions as per page on fresh install

1. the ltsp-config lts.conf command kicked out an error that the sample file could not be found.


You can find the example lts.conf file there for now:
http://bazaar.launchpad.net/~ltsp-upstream/ltsp/ltsp-trunk/view/head:/server/configs/lts.conf

I'm sure it'll be included in Debian's LTSP packaging in a few days so
the wiki page will be valid then. :)


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David Groos 05-30-2012 03:07 PM

Simpler method for fat/thin client setups
 
Preparing to think about next year...

Since the server would need to run in pae mode, how does that affect how much memory you can have on the server?

Also, what's your experience with a server serving 30 fat clients?* Can you use 3 gigs RAM on the server since the clients are Fat?*


Thanks for simplifying things alkisg!
David G

On Wed, May 30, 2012 at 9:43 AM, Alkis Georgopoulos <alkisg@gmail.com> wrote:

Στις 30/05/2012 02:29 μμ, ο/η Dean Mumby *γραψε:


Thanks for link , have followed instructions as per page on fresh install



1. the ltsp-config lts.conf command kicked out an error that the sample file could not be found.




You can find the example lts.conf file there for now:

http://bazaar.launchpad.net/~ltsp-upstream/ltsp/ltsp-trunk/view/head:/server/configs/lts.conf




I'm sure it'll be included in Debian's LTSP packaging in a few days so the wiki page will be valid then. :)



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Alkis Georgopoulos 05-30-2012 03:52 PM

Simpler method for fat/thin client setups
 
Στις 30/05/2012 06:07 μμ, ο/η David Groos *γραψε:

Since the server would need to run in pae mode, how does that affect how
much memory you can have on the server?


Hi David,

as I write on the ltsp-pnp wiki page, PAE kernels support up to 64 Gb
RAM. And since fat clients don't consume almost any server memory
anyway, that memory would only be useful for the thin clients in a
mixed-mode environment.



Also, what's your experience with a server serving 30 fat clients? Can
you use 3 gigs RAM on the server since the clients are Fat?


Sure, 3 Gb server RAM would be enough for 30 fat clients. Do some
benchmarks about disk speed and network bandwidth though, you might e.g.
see that a second PCI-e NIC on the server (with bonding) proves useful.


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Dean Mumby 05-30-2012 04:41 PM

Simpler method for fat/thin client setups
 
I have a problem with DNS , the client boots up and /etc/resolv.conf on the client gets written as dnserver 127.0.0.1 , even through the original file on the server points to the gateway ip. I tried setting it in lts.conf DNS_SERVER=192.168.4.1
but that doesn't seem to help


second problem is I don't see the network printers setup on the server on the thin clients ??



----- Original Message -----
From: "Alkis Georgopoulos" <alkisg@gmail.com>
To: "David Groos" <djgroos@gmail.com>
Cc: "Dean Mumby" <dean@mumby.co.za>, edubuntu-users@lists.ubuntu.com, ltsp-discuss@lists.sourceforge.net
Sent: Wednesday, 30 May, 2012 5:52:40 PM
Subject: Re: Simpler method for fat/thin client setups

Στις 30/05/2012 06:07 μμ, ο/η David Groos *γραψε:
> Since the server would need to run in pae mode, how does that affect how
> much memory you can have on the server?

Hi David,

as I write on the ltsp-pnp wiki page, PAE kernels support up to 64 Gb
RAM. And since fat clients don't consume almost any server memory
anyway, that memory would only be useful for the thin clients in a
mixed-mode environment.

> Also, what's your experience with a server serving 30 fat clients? Can
> you use 3 gigs RAM on the server since the clients are Fat?

Sure, 3 Gb server RAM would be enough for 30 fat clients. Do some
benchmarks about disk speed and network bandwidth though, you might e.g.
see that a second PCI-e NIC on the server (with bonding) proves useful.

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