  This paper presents a proposed model for database replication model in
private cloud availability regions, which is an enhancement of the SQL Server
AlwaysOn Layers of Protection Model presents by Microsoft in 2012. The
enhancement concentrates in the database replication for private cloud
availability regions through the use of primary and secondary servers. The
processes of proposed model during the client send Write/Read Request to the
server, in synchronous and semi synchronous replication level has been
described in details also the processes of proposed model when the client send
Write/Read Request to the Primary Server presented in details. All the types of
automatic failover situations are presented in this thesis. Using the proposed
models will increase the performance because each one of the secondary servers
will open for Read / Write and allow the clients to connect to the nearby
secondary and less loading on each server. Keywords: Availability Regions,
Cloud Computing, Database Replication, SQL Server AlwaysOn, Synchronization.
