Is there anyway for one Virtual Server to access the main host, or another Virtual Server?

Or would they be totally 100% independent?

What are you using? Do you know what the IP address is for each VM?

Xen on CentOS, I know the other IPs

Have you tried the Xen wiki?
Have you ried other distributions such as Debian or Arch and those wiki's howto's for information?
Gentoo documentation should also have coverage.

http://www.linuxtopia.org/online_boo...k_devices.html

Umm, sure just as it is possible for one physical machine to "access" another physical machine: usually this is done with networking...

Evo2.

I guess it comes down to what you mean by the word 'access'. Back in the day, in the year 2000, I was running windows 2000 on a dell inspiron 8000 laptop 866mHz, with 768MB ram and using vmware workstation to host an NT server running SQL server and an Accountmate accounting package all in a VM with 256MB ram allocated to it. This setup duplicated a similar live system running in the company's IT dept on three seperate boxes. And to be honest there wasn't much difference in the response time between accessing the realtime live system or my virtual copy. Because the virtual machine was always closed in a saved state I didn't have to boot it and the SQL server was always running whenever I opened the NT server. I could download the 'live' data to my machine on a friday evening,work on it, mainly amending the chart of accounts, and move the accounting entries to the new accounts and then upload the amended data to the live system early on a Monday morning before the accounting department came into work.

Just so you know, the system was running in parallel with an old Peachtree accounting system, that I/we were replacing - so it always had to balance (not that I didn't have a duplicate copy of the Peachtree data and program on my machine). As long as I got the passwords right for all the various modules, one of which was still be modified as we went along, it all worked extremely well.

However, if by 'access' you mean can a VM issue instructions to another VM and/or the host, then that is a rather different question - for instance it would be easy to set up a system to email logs and or other data from a VM to the host and or another VM, whether it would be so easy for the second VM to parse the log file so recieved and react accordingly would be a rather more complicated issue. Obviously emails sent to the host could be acted upon by the human operator, i.e. you. NAT is your static IP address friend, or at leat he was mine!

Hope this helps