[K12OSN] Curious Question

[Les Mikesell]

On Fri, 2004-07-09 at 12:12, Matthew Ross wrote:
> Here's a question...
> 
> My boss, as much as he loves our LTSP server so far, would love to have 
> a hot-swap backup server as well. Basically, he's wondering if there is 
> a way to have a fault-tollerant setup for an LTSP server.

It can be done, but I've generally found 'warm' spares to be
more practical.  That is, you keep another box loaded but
not active and leave instructions to activate it in case
the primary fails.  Activation might involve running a
script that changes the IP address and starts DHCP. 
Server-class PC's don't fail often and the software to
do automatic failover is as likely to cause trouble as
to prevent it.

> Since the /home directories will be on a diffrent server alltogether, 
> the user's information would still be there even if our LTSP server crashed.
> 
> And I understand that the user's current sessions would fail in the 
> event of a LTSP server failure, but if they rebooted their thin clients, 
> is there a way to have a "backup server" jump in and take over?

If you are running in a single-nic configuration, one approach
would be to split the DHCP range and leave both boxes on line
all the time.  Then you would get some load-sharing between
servers as the clients get assigned by whichever answers
faster and if one fails completely, the other would continue
to work and would pick up all the clients as they reboot.
If both mount a common /home, the clients should not
see any difference.  You'd want to make at least an equal
effort to make the home directory server robust - perhaps
RAID drives either in an external case or hot-swap carriers
with a spare server available to take over by moving the
disks.

---
  Les Mikesell
   les at futuresource.com