[NCLUG] mirroring directories

[dobbster]

Hi,

What's the simplest way of mirroring a directory hierarchy on one system
to another system, real time?

I'm working with two web servers: One is through a web hosting service,
and the other is our own web server, which is running multiple webs
through virtual hosting.  Via ftp or otherwise, I'd like to mirror the
site's home directory on the first system into some directory on the
second system.  The site gets quite a few hits, and my CGI scripts
modify files every few minutes or so on the average.  Therefore, it'd be
ideal to mirror "real-time" or at least have it update changed files
every, say, minute or two.

My goal is to migrate the site to our own web server, and modify DNS to
point to the new system.  I could tar/gzip/ftp the directory, but by the
time the changes to DNS have propagated through, things will be out of
sync.

I hope I've worded this problem clearly enough.  Is there some tool for
doing this?

Thanks in advance,

Mark (dobbster at frii.com)