Additional virtual (or not) DC?

[djones]

We have around 100 xp clients (roughly 50/50 desktop/wireless split) and a single 2003 server with AD etc, SIMS, WDS... We also have a new, spare Dell Optiplex 755 that I thought could be used to provide a bit of redundancy, server wise. I would also like to utilise the multicasting features of WDS in server 2008 therefore...

 

I am considering using 2008 as an additional domain controller (and moving the current WDS setup to that) but am interested in setting up a virtual DC so that I'm not tied to using the Optiplex in the future. So, my real questions I suppose are:

 

• what would you use as the host operating system in this case?
  
• how have you setup virtual servers to provide the most/best redundancy?
  

 

I know this thread could quite easily be split over several different forums/threads so sorry if it is a bit....well...you know!

 

Dave

[dhicks]

> what would you use as the host operating system in this case?

 

I use Xen running on CentOS 5.1. I tried with Ubuntu 8.04 but it just plain hung all the time. Xen with CentOS is dead easy, you simply select the "virtualisation" option when installing from the CDs, it'll be running right from the start. I don't actually run Windows on Xen, but I'm sure if you type "install windows xen" into Google you'll get a couple of how-to guides.

 

> how have you setup virtual servers to provide the most/best redundancy?

 

DRBD (on top of LVM for added flexibility and the ability to take snapshot backups of an entire, running, VM). Nice, mature-looking open source project - the documentation is actually readable and comprehensive. Basically real-time mirrors Linux block devices (i.e. disks) between machines. Best performance if you can have a dedicated network link between the machines instead of going through a switch, but that's hardly difficult or expensive (buy two extra Gigabit network cards at £10 each).

 

DRBD's documentation reckons you can set up so that one server will take over from another that goes down within 800ms, but I have yet to test this in practice...

 

--

David Hicks

Edited June 3, 2008 by dhicks