SUMMARY: Redundant Servers

From: Chad Rytting (ryttinch@sol.slcc.edu)
Date: Tue Nov 17 1998 - 07:59:13 CST


First things first, I would like to appologize for taking so long in
getting this summary back out to the list. I appreciate all that
replied to my question regarding redundant servers:

Bryan Blackburn
Rich Kulawiec
Kevin Sheehan
Chris Tubutis
Michael Wang
Todd M. Wilkinson
Laurent Ulmi
Dwight Peters
Sudheer Tummala
Jason Harrell
Samuel Godbillot
sunsrv
Seth Rothenberg
Louis Hoo

My original question was:

> Does anyone know of a good package to use to create a redundancy of
> servers. I appologize if this is a fairly basic question, but I am
> rather new to this world, and am in a need of putting in place a
> redundancy on our web servers.

The majority of responses to this problem were commercial software
packages. I am in the process of following up on all of the ideas that
people gave me. I have listed below the web sites of the companies
along with the packages that they provide for redundancy in a server
environment, after which I have listed specific comments that don't deal
with commercial software packages.

http://www.f5.com - BigIP
http://www.veritas.com - Veritas FirstWatch
http://www.sun.com - Solstice Disk Suite
http://www.veritas.com - Veritas Volume Manager
http://www.qualix.com - Qualix HA+
http://www.cisco.com - Cisco local director
ftp://ftp.mindspring.com/users/mwang/unix-prog - niftp
http://www.resonate.com - Dispatch

Todd Wilkinson wrote:

        First you asked a very broad questions, and two there are a lot
of
        answers.

        You need to ask yourself, just what part or all do you want to
make
        redundant. You could for instance run two web servers on one
box,
        run a proxy/caching/redirection server in front of it and if one
"web
        server - the process" fails it will roll over to the next. In
the case of
        some of the higher end sun's i.e the 3500 and higher you can
make just
        about every part in the box redundant and hot-swappable.

        You could by two smaller Sun's put a web server on each, worry
about
        data relication through something like rysync/scp/rcp/rdist and
        then place a proxy/caching/redirection server in front of both
of them.

        You have a lot of options, some cheap but you do a lot of the
        work,setup, diagnostics and event handling yourself. Or you
could
        go outright and by a real nice setup of two server and place
something
        web director server purchased in front of the two and let it and
the
        vendor take care of much of the work.

Jason Harrell wrote:

One way you might one to accomplish such a thing would be to basically
setup
up two or more web server with the same exact content and have whatever
database(s) they may access local to their machine (e.g. disk directly
attached to each machine I would not recommend NFS here for performance
reasons). Next, you need to get an IP load balancer such as
LocalDirector
from Cisco (go to www.cisco.com to learn more about it). This will
balance
the load or "hits" between both you web servers. Of course, for
performance
you would probably want this setup hanging of an Ethernet switch.



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