[K12OSN] I need opinions....backup idea for when Terminal server down and I'm not around

Christopher K. Johnson ckjohnson at gwi.net
Sun Jul 10 11:45:10 UTC 2005

David Trask wrote:

>I worry about what happens if the Terminal Server fails while
>I'm far away (like at Linux World).  Until now they could boot into
>Windows and still have the class go on (remember I'm a computer teacher as
>well as the tech director and have a full slate of classes...grades K-8
>over the course of a week....I see about 450-600 kids)  When I go to
>dedicated thin-clients...K12LTSP server goes down...they're dead in the
>water.  So....
You have other points of failure that would be of equal impact, and 
different client machines would not protect against any of them failing:

    * Your ethernet switch in the closet.
    * Your Internet Firewall (also a Linux box)
    * Your dns server for the private network (I think that's on the
      Firewall in your case)
    * Your Internet service router (probably a Cisco)

If it were me - I would spend the money on redundant hardware in the 
LTSP server, and make other configuration changes for higher 
availability of the server:

    * The most likely server failure is a disk drive - use software raid
      disk and hot-plug disk drives if possible
    * The next most likely server failure is a power supply - servers
      with dual redundant power supplies are nice, or at least with a
      hot-pluggable power supply if not redundant.

On the software/configuration side of things separate filesystems for 
/var, /home, /tmp, and quotas on /home for users will protect against 
space problems bringing things to a grinding halt.

Make sure you have good UPS power backup and surge suppression for all 
your server/switch/router equipment, with sufficient capacity for 
everything running on it.

You can make services a bit more robust by adding a caching secondary 
dns server somewhere on your private network (perhaps on your LTSP server).

DHCP is another such service, slightly less critical if you set long 
leases, but essential just the same.  Two DHCP servers configured for 
failover are now supported, although I have no personal experience yet 
with how well that works.

The support for clustering and cluster based file systems continues to 
improve in FC4, and I would anticipate someone perfecting a clustered 
solution for LTSP in the next year.  So probably a redundant failover 
pair of LTSP servers with the filesystem and quota configuration 
suggested above would be your ideal solution.  Until then you can still 
implement the other suggestions to reduce the highest failure risks.


   "Spend less!  Do more!  Go Open Source..." -- Dirigo.net
   Chris Johnson, RHCE #807000448202021

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