load sharing

[Shelley Wilmoth]

In article <1991Feb6.173736.11922 at bwdls61.bnr.ca> pww at bnr.ca (Peter Whittaker) writes:
>In article <25860 at adm.brl.mil> pjw at usna.navy.mil, , jw at math30, (Peter J. Welcher (math FACULTY)) writes:
>
>(after many deletions...)
>
>>
>>I have a question, especially for the academic readers of the group. 
>>(And it may just be I'm missing the obvious, or re-inventing a wheel.)
>>
>>Writing a script that does something with rwho is a possiblity, but there's all
>>
>>I've written a C program that forks (to get around timeout delays) and then
>
>If you are going to force people to login to a single front-end host, then
>why not write an program that keeps track of who has been assigned to each
>machine, then assigns each new user to the least-busy machine? (i.e. using 
>rlogin, or what have you).  When a user logs out of the assigned machine, 
>strike them from the "assigned machine" table.
>
>As long as your users are doing roughly the same amount of work (which should
>be true if they are all working on the same assignment) your machines will
>be more or less equally loaded.
>
>It's not terribly elegant, but it would work.  If you wanted to double check
>the load on a machine before assigning a user to it, query it via UDP (if you
>are on a LAN, UDP should be fairly reliable).  If it says it is too busy, 
>query the next machine in your "machine assignment" table.
>
>There are more elegant solutions, but this one should be quick to write and
>should work passably well.

If users will not always be working on the same system each time they
log in, and if they will be saving their work in files, you will want
to be sure they have access to those files no matter what machine they
log on to.  For example, user Jones logs on and is assigned to System A,
does some work on the assignment, saves it to a file system local to
System A, then logs off and goes to class.  Later, he logs in again to
complete his work, but is assigned to System B because it has the lesser
load at the time.  He will wish to somehow access the files he stored on
System A.