I have purchased 2 identicle HP servers at the same time. I have built the first server with 2003 SBS importing all old emails into exchange and set-up on a RAID 1 config using 2 x 160GB drives. This server is now running perfectly. It is important to know at this stage that the server has no client machines attached as the server is mainly for exchange only. All of the staff connect to exchange using OWA and some use Outlook Anywhere over HTTPS. The question I have is the client wants a failover system that should the first server be unavailable, the second server kicks in automatically. This is now when I am lost. What I have done so far is to wait for the first server's RAID to finish building so we now have 2 drives with an identicle image on. I then removed the secondary hard drive from the the first server and replaced it with a formatted blank 160Gb drive. I then rebooted the server and rebuilt the RAID from the master drive to the new secondary drive. This seems to be going fine. My plan is to install the above hard drive from the first server into the second physical server, set up the RAID 1 using the primary hard drive with the above image and a spare formatted secondary drive. Then to rebuild the RAID again, on the second server. The main reason I have done this is so that the user account SID's are the same on both servers which I would not have got by building the second server from scratch. I then plan to change to OS key on the second server and activate this accordingly. How am I going to keep the second server running as well as the first server both running up-to date Active Directory (with identicle SID's) and Exchange mail so if the first server fails for any reason, the users will not see any loss of data or services and all of their emails will be kept up-to date and readily available over OWA and / or Outlook Anywhere? It is imperitive that the user account SID's are the same on both servers. I need a system that if I add a new member of staff or make any AD changes such as passwords or permissions, both servers again, have the same SID's and any changes in AD are instantly changed on both servers. Is there a way of autoamating this for both servers. I cannot believe my client is the only company in the world that wants to achieve this failover service and therefore someone out there must have set this up in the past. Any help would be greatly appreciated. Many thanks Dan