LTSP chroot not used

White, Joseph jwhite at
Tue Feb 9 21:08:35 GMT 2010

Thank You, that was the missing piece of information that cleared up my confusion.


From: David Groos [mailto:djgroos at]
Sent: Tuesday, February 09, 2010 12:15
To: White, Joseph
Cc: edubuntu-users at
Subject: Re: LTSP chroot not used

Hey Joe,
I can give the non-programmer perspective, probably wrong in details but conceptually correct.  Sorry if I'm being too basic.  Someone in the know, please correct my mistakes.

The main folder on the server for the thin clients is /opt/ltsp/.  Inside this folder there are 2 folders: /opt/ltsp/i386 (in my architecture) and /opt/ltsp/images/.  The latter contains a disk image that, during thin client boot, get sent to the thin client and is booted there (right?).  I'll use the notation, i386 but substitute in your arch.

The former, /opt/ltsp/i386/contains a complete (well, somewhat stripped down) file system.  If you look in this folder, it looks like you are opening up the root folder of a computer.  This folder and its contents are the source of the image mentioned above, '/opt/ltsp/images/i386.img'.  (Check the size of this file, it's of course big.  Mine's 1.1 gigs.)

To turn this file system, opt/ltsp/i386/ into an image, you run the command, 'sudo ltsp-image-update' and the computer basically makes a new copy of this file system to replace what is currently in /opt/ltsp/images/.

So, you sometimes need to 'update the chroot', that means you update the file system in /opt/ltsp/i386/, then run the above command to make an image of this newly updated file system.  To update the chroot file system you need to... well, check the wiki info for those details.

So, if you want to see/interact with the file system that is running on the thin client, get into local console mode (I do this by pressing Ctrl-Alt-F2 because alkisg helped me set it up that way).  You can't see the local file system by opening up terminal because that will only show what's on the server...

Hopefully this wordy saying-the-same-thing-in-another-way was helpful.

Good luck and things do get easier!

On Tue, Feb 9, 2010 at 10:44 AM, White, Joseph <jwhite at<mailto:jwhite at>> wrote:
Hi All,

Looking at the LTSP Chroot Environment section of
It sounds like the new root file system is mounted from /opt/ltsp/<arch> , at what point does the real / get mounted? I'm sorry if this is
obvious to everyone but me.

 LTSP Chroot Environment:
11.  Up to this point, the root filesystem has been a ram disk. Now, the /init script will mount a new root filesystem
via either NBD or NFS. In the case of NBD, the image that is normally loaded is /opt/ltsp/images/

If the root is mounted via NFS, then the directory that is exported from the server is typically
/opt/ltsp/<arch>. It can't just mount the new filesystem as /. It must first mount it to a separate
directory. Then, it will do a run-init, which will swap the current root filesystem for a new filesystem. When
it completes, the filesystem will be mounted on /. At this point, any directories that need to be writable for
regular start up to occur, like /tmp, or /var, are mounted at this time.



-----Original Message-----
From: edubuntu-users-bounces at<mailto:edubuntu-users-bounces at> [mailto:edubuntu-users-bounces at<mailto:edubuntu-users-bounces at>] On Behalf Of Scott Balneaves
Sent: Monday, February 08, 2010 12:51
To: edubuntu-users at<mailto:edubuntu-users at>
Subject: Re: LTSP chroot not used

On Mon, Feb 08, 2010 at 12:41:35PM -0700, White, Joseph wrote:
> It looks to be set correctly... Ideas?

This is exactly how ltsp is supposed to operate.  The chroot is for the thin
client to boot.  The session runs on the server.  Please see the docs at:

For an explanation of the boot process.

> 2. Also, the main config lts.conf has no entries what so ever, is that because the LTSP Thin Client work out of the box?


> 3. Also the lts.conf has a note that the lts.conf file should be located in /var/lib/tftpboot/ltsp/i386, the file did not exist there, so I'm guessing if you needed to use lts.conf you would create it there?


> Any Help Greatly Appreciated.

In short, you have no problem, things worked out of the box as designed :)



Scott L. Balneaves | The mark of an immature man is that he wants to die nobly
Systems Department | for a cause, while the mark of a mature man is that he
Legal Aid Manitoba | wants to live humbly for one. -- Wilhelm Stekel

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