[cobalt-users] "Load balancing" w/ DNS and rsync - theoretically....

["Rick Ewart" <cobalt@xxxxxxxxx>]

I read something and had an idea. Thought I would pass it to the list to
flesh out into a viable solution....

I read in a linux mag this past week about using a DNS round robin technique
to sorta balance requests to servers. Essentially, two A entries for the
same domain, pointing to 2 different servers. Each subsequent DNS query
would "round robin" to the other server. Of course this is not a true load
balancing solution as it doesn't account for true server load (or even
availability), but it should work as an ad-hoc load balance solution -
particularly if its a temporary surge in traffic. Certainly a cheap
solution - free.

I started wondering how I might implement this in the real world where
people update servers and such.... Seems like rsync could be the candidate
for keeping the two servers updated with the current information... Client
publishes site, then it is rsync'd to second server. But rsync is one way,
correct? I don't have any real experience with it - haven't had the need
YET.

If rsync is only one way, there is the danger that the client posts to
server 2 instead of server 1, and then the next rsync update overwrites the
changes. I guess this could be solved by using IP based sites so that one
could publish to a specific server IP instead of domain name?

The other question/concern would be how much overhead rsync requires and if
that would really eat up the gains you make in the load balancing. Guess
that depends on how often it runs....

It seems like this might be a useful tool and/or discussion, if anyone is
interested. If not, I will just go back to my work.... :)

Take care.
Rick