For High availability, I think and I suppose service desk application can be installed on different servers like 3 servers and then using Load Balancer to access the server simultaneously on a single IP address. I think this can be achieved in as much as the Database is central... maybe on a cluster in the enterprise. 

My concern now is the attachment for the cases and assigning of case numbers. How can this be responded to? Is it done by the application or by the database? Can the path to attachments on all the applications be changed to a central location and is the case numbers, requesters, technician and the app settings local or on the database. How can this be achieved?

Regards