At the end of the year, we are to replace some servers for a customer. They are thinking about disaster recovery and damage limitation if one of their buildings should flood, or go up in flames etc., and because of this they are going to have a physical server and SAN in their main building and a duplicate physical server and SAN in a satellite office, both of which are connected via a fibre link and will replicate data.
The "plan" is that one server/SAN will be the primary, and the other will act as a backup - the two will replicate. So far so good - users will still be able to log on and access data.
Now, my question is this. Supposing, the fibre link between the two buildings goes down or gets cut (as one recently did at this site - by a careless contractor!). If one combination of server/SAN is serving the main building and the other server/SAN is serving the satellite office, what happens when the fibre link is restored?
The physical servers will have 4 Hyper-V guests, 3 of which will have SQL applications such as CRM, SharePoint, Document management etc....
My concern is will one set of data overwrite another, or will the SQL databases be able to "merge" any differing records with the same record IDs etc?
I've never done anything like this before and I just want to understand what would happen in this scenario.