Designing Data Storage Architecture - datasync

http://www.infoq.com/news/2011/10/sql-azure-data-sync

Microsoft has announced a preview release of SQL
Azure Data Sync for all SQL Azure subscribers. Users can now setup synchronization across SQL AzureDatabases in multiple data centers as well as Cloud-to-on-premise
synchronization with a simple point-and-click interface.

SQL Azure Data Sync is based on the Microsoft Sync framework and allows synchronization between SQL Azure and SQL Server or other SQL Azure databases. It has been
in CTP for a while, on a registration and invitation basis. The following things are new in this release -

Improved Management Portal with graphical interpretation of the sync topology, allowing to configure, manage and monitor it
Better flexibility with option to filter only a subset of a table columns or specific rows and sync
group configuration
Unlike earlier CTPs, this release is available to all SQL Azure users for trial, without a separate registration process

The synchronization can be setup at predefined intervals, which can be controlled at the level of a sync group – a group of tables that need to be synchronized together. For two-way synchronization, conflict
resolution can be set to Hub wins or Client wins.
The service is targeted towards various enterprise scenarios such as -

Co-locating data geographically with applications around the world, for better responsiveness
Scale-out data into different databases for different workloads
Extending on-premise applications with cloud applications for better sharing of data
Share data between multiple locations

There is no separate cost for this service, although the normal data transfer charges for SQL Azure will apply. You can see this article for the
cost considerations.

Sync Framework is a data synchronization platform that works for data in any data formats, transfer protocols and network topologies. It allows for distributed applications
to be developed which can synchronized data across multiple platforms.