nagy%43198.hepnet@LBL.ARPA.UUCP (03/23/87)
>In the next few weeks I will be installing a Local Area VAXcluster >which will have an 11/750 as a boot node and six VAXstation IIs as >satellites. I also have a DECserver 100 (and a DECserver 200 on the >way) which will allow terminal access to the cluster. >Here's the problem. I want to set up the DECserver so that the >user will say "Connect Cluster". It is my understanding that the >DECserver will then connect the user to the machine that is least >heavily used at the time. The problem that I forsee is that the >machine that the DECserver determines is "least heavily used" will >be a VAXstation with two users on it (all our VAXstations have >a two user maximum). I can't imagine that the DECserver would be >smart enough to avoid this, so it would dump the user to the >VAXstation, which would then, in turn, say "sorry, maximum >number of logins reached" and dump the user back to the DECserver. >Voila. The user is locked out of the cluster. I believe that the way this works is that each VAX with the LAT software enabled multicasts a message saying "I'm available and I have XXX service rating and I'm a member of service YYYYY" where YYYYY is the VAXCluster service name used by all the nodes in the cluster. The DECServer then selects the available node with the "highest" service rating. So, I'd assume that if the interactive limit was reached on a node, it would multicast a message either "I'm not available for new connections" or "My service rating is now 0 or -infinity or whatever". Balanced against this is a bias within the DECserver to start new connections to a node to which it already has 1 or more connections for more efficient communications. >2) Modifying the DECserver software so that it will do one of > two things. "Sources? Sources? We ain't got no stinkin' sources!" The DECServer software is available only in binary for downloading into the DECServer. The LAT software for VMS isn't even on the fiche. So.....