Microsoft has provided the industry with yet another proof point that for the bulk of enterprises and enterprise workloads, moving to the cloud is going to be a hybrid experience. Now in preview, SQL Server Stretch Database allows customers to "stretch" data to the Azure cloud, managing it more effectively and saving money. Here are the details from an official Microsoft blog:

Applications and data are at the heart of how organizations drive competitive value and improve efficiency. However, this digital transformation is resulting in an explosion of data. Enterprises have to figure out how to get a handle on this data – how to increase their storage capacity and keep their data safe and secure, without drastically increasing IT costs.
 
Microsoft believes a hybrid cloud approach can offer unique ways to manage this data proliferation. We believe you should be able to take advantage of the best of the public cloud and the best of your on-premises technology. 

SQL Server 2016 with SQL Server Stretch Database service, a new Azure companion service, enables you to dynamically stretch your on-premises warm and cold data to Azure for virtually endless compute capacity and storage. Now you can keep as much data as you need in the cloud, up to 60 terabytes per database in preview, without the high costs of traditional enterprise storage. The Stretch Database service makes remote query processing possible by providing compute and storage in a way that’s completely transparent to the application.

The service incorporates Always Encrypted technology. This encrypts information on-premises before moving it to Azure, while encryption keys stay in-house as well. 

Microsoft has also unveiled Transactional Replication to Azure SQL Database, with which customers can backup data to SQL Server instances running on Azure; and StorSimple Virtual Array, a virtual machine version of StorSimple. 

Analysis: Hiding the Seams

"Plenty of database vendors are moving into the cloud, and most give three, separate options: On-premises, private or public," says Constellation Research VP and principal analyst Doug Henschen. "Microsoft is eliminating, or at least hiding, the seams between these options."

The key benefit of SQL Server Stretch Database is that it's not about creating additional database instances, Henschen adds. "The hot data stays on premises and the warm and/or cool data can be automatically moved into Azure," he says. "The benefit is that your database still looks, acts and effectively remains a single database instance, so users and applications won’t know the difference."

The last point underscores the crucial difference between SQL Server Stretch Database's approach to handling cold data—moving it to lower-cost storage but keeping it available for querying—compared to archiving data to less readily accessible formats such as tape or deleting it altogether. In any case, enterprises may not have the option of deleting some data due to regulatory requirements. 

SQL Server Stretch Database can be used to migrate entire database tables to Azure, but Microsoft has also provided the flexibility to move individual rows, in cases where a table contains both cold and warm data. Existing queries don't have to be rewritten and while there will be some latency when querying the data held in Azure, it is minimal, according to Microsoft.

Other potential benefits to SQL Server Stretch Database include the ability to pare down on-premises database tables that have become unwieldy in size, which in turn could cut down on on-premise system backup and maintenance, Microsoft notes.

Meanwhile, the new StorSimple Virtual Array option, "brings virtualization into the play book along with the previously available on-premises and Azure Cloud options," Henschen adds. "The benefit is more choice, offering customers greater deployment flexibility and savings on infrastructure while still keeping warm or sensitive data behind corporate firewalls."

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