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Benjamin Nevarez

Are You Using Scalable Shared Databases?

Did you know that you can share read-only databases between several instances of SQL Server?

Scalable Shared Databases is a very interesting SQL Server feature that many of us seem to almost have forgotten about it. Available for the first time in SQL Server 2005 and originally described on the Microsoft KB article 910378, it was later fully documented on Books Online. This Enterprise edition-only feature allows a read-only database to be accessed at the same time by two or more SQL Server instances (maximum recommended is 8). This configuration offers some performance benefits by allowing each of these instances to use its own resources like memory, CPU, and tempdb database. Scalable Shared Databases are used as reporting databases.

The concept behind Scalable Shared Databases is very simple: you copy a detached database to a volume, configure that volume as read-only, and then you can attach this database by several SQL Server instances. A shared database will look like a regular read-only database in Management Studio.


By the way, it would be interesting to know if Microsoft plans to add additional functionality to this scalability feature or to extend it to read-write databases, perhaps something similar to what Oracle RAC is already doing.

For more details, especially on restrictions and configuration, see the ‘Deploying a Scalable Shared Database’ entry on Books Online.

Published Friday, October 30, 2009 1:26 AM by Ben Nevarez
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About Ben Nevarez

Benjamin Nevarez is a SQL Server MVP and independent consultant based in Los Angeles, California who specializes in SQL Server query tuning and optimization. He is the author of "SQL Server 2014 Query Tuning & Optimization" and "Inside the SQL Server Query Optimizer" and co-author of "SQL Server 2012 Internals". With more than 20 years of experience in relational databases, Benjamin has also been a speaker at many SQL Server conferences, including the PASS Summit, SQL Server Connections and SQLBits. Benjamin’s blog can be found at and he can also be reached by e-mail at admin at benjaminnevarez dot com and on twitter at @BenjaminNevarez.
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