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Re: [K12OSN] Load Balancing between servers

Another "poor man's" approach is to write wrappers for the apps you want
to distribute.  If, for example, you want to distribute netscape instances
so as to even memory load, you could write a wrapper for netscape that
checked some file or files that would indicate memory usage on each server
and "rsh" to the server with the most available memory.

A daemon process on each server would update the file or files every so
often (like 30 seconds or so).  Assuming there is a common NFS-mounted
file system, this approach isn't too hard if you have basic scripting

A more ambitious approach might be to create a "shell" launcher using
a language like perl that could use network protocols to query the
servers.  Then a student could say "launch netscape".

Just some ideas....


Jay Kline wrote:
The problem with this idea is the concept of multiple, persistant connections. When using DNS round robin in this case, it will decide at boot time which server to use (flip a coin), and will always use the same server. The conditions may be right such that one server gets all the abuse, while the other gets nothing. (The chance may be greater than you think. If queries happen in pairs, as they often do, you will always get the same set) I will assume for the moment that you dont need to use any real services that require multi-use to the same box (ie running an SQL server or talk daemon)- then what you really want to load balance, is when someone starts a new process, it can migrate to the server with the lowest load. I would recomend using MOSIX for this, if possible. (You could even use the workstation CPU's potentially)

If setting up MOSIX is too much work, you can always try the "chooser" method. XDM has a chooser which brings up a menu of availible XDM server on the network you can connect to, and will show the number of logged in users and the load. That way people can choose for themselves.


On Tuesday 30 July 2002 3:29 pm, Brent D. Norris wrote:

For the time being, I am going to set the servers in the closet with the
wiring, and patch half of the lab into one server, and the other half
into the other.


My friend maxx (http://maxx.zweix.com) gave me this idea for a load balancing solution. Thought I might share and ask for comments.

In a giving situation where you have two servers (assuming identical
passwd, shadow, group) one alpha and one beta.  In DNS have an entry for
each server:  alpha.ltsplab.com  and beta.ltsplab.com

then with each entry add a cname entry that points to gdm.ltsplab.com
then point your gdm login configuration option to gdm.ltsplab.com.

Then DNS will do alternating resolutions to alpha and beta.  This will
give a "poor man's load balancing" :)

Anyone have any thoughts or problems with this idea?

Brent Norris (Net-Tech.BG-Afni) http://brentnorris.net
H: 270.563.9226        W: 877.448.2364 x3021
Pager: 270.610.0002 (text message www.arch.com/message/)

Don Christensen       Senior Software Development Engineer
djc cisco com         Cisco Systems, Santa Cruz, CA
  "It was a new day yesterday, but it's an old day now."

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