[SunRay-Users] RE: Need Suggestion in Failover Group (Lars Tunkrans)

Neal A. Lucier nlucier at math.purdue.edu
Thu Apr 3 10:15:48 EEST 2008

Lambertus Setiawan Wardana wrote:
> as master not one as master and one as slave, and from what I heard in the
> net some of people complaining that distribution of the session is not
> balanced since whichever the server goes up first, that server will be
> stormed by the DTUs and in the end we have to manually make adjustment to
> the distribution and we cannot afford it...

There are DHCP and DNS settings that are lists of IP addresses and the 
DTU randomly selects one to connect to and all the DTUs don't flood the 
first server.  Now if the servers are all off and you bring one up way 
before the other one than all the DTUs will be on that one.

This isn't that big of a deal:  the server gets flooded and stops 
responding to DTUs that aren't already connected to it; however, the 
DTUs will connect to the 2nd server.

If you have NSCM or are using smartcards, then on each login a load 
balancing event takes place.  Initially all the "real" DTU sessions will 
be on the 2nd server because the 1st is supporting so many that are just 
sitting at the greeter.  As the 2nd server becomes used, the load 
balancer will switch and start to launch sessions on the 1st server.

There is no manual intervention to get an equal load across 2 servers in 
an FOG.  Initially the load may be skewed because all of the DTUs are 
connected to the 1st server, but this will have no effect on users 
perceived usability of the 2 servers since a load balancing event will 
take place at login.


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