On Thu, 20 Mar 2003, Gordon Messmer wrote:

..
> The new system cost about $15000.  It is built with an NFS backend 
> running Red Hat Linux 7.3 on a 1TB RAID 5 set attached to a 3ware 7500 
> card, one 1.8 Ghz CPU and 1GB of RAM.  There are two Courier servers 
> configured identically, load balanced with DNS round-robin.  Each has an 

I would strongly suggest taking a good look at:
http://www.linuxvirtualserver.org/Documents.html
specifically 
http://www.linuxvirtualserver.org/VS-NAT.html

DNS round-robin has /so/ many problems -- you have to set the ttl
incredibly low for it to work at all, and /many/ email clients /cache/
the IP beyond the ttl.  Thus, if you name your servers A and B, and A
goes down (and A is the "primary"), many clients will continue trying to
contact A despite it being down and the ttl having long expired.

The LVR/NAT and LVS/DR solutions are much "better" from a high level
perspective. Heck, you could probably get away with a Pentium 200 level
machine as the NAT/DR "router" - it just passes and mangles packets.

--
Applying computer technology is simply finding the right wrench to
  pound in the correct screw.

Jon Nelson <[EMAIL PROTECTED]>
C and Python Code Gardener


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