Building Scalable Analysis Services Applications - Microsoft SQL Server 2008 Analysis Services - page 466

Shared Scalable Databases

Analysis Services 2008 introduces new set of functionality that makes it easier to imple-
ment variation of the farm where multiple front-end servers are sharing a single copy of a
database residing on the read-only shared storage (SAN, NAS, and so on). The front-end
servers in this configuration are running as part of the network load-balancing cluster and
presented to the user as a single server.

To make this scenario possible, Analysis Services introduces several new technologies:

. Read-only —Ability to mark database as read-only to disallow any updates to a data-

base to make it possible for several servers to point to it.

. Attach\detach for a database —Ability to detach database from a server into and

ability for several servers to attach to a single read-only copy of a database.

. Database location —To make it possible for a database to reside in a separate folder

outside of the data folder, such that front-end servers can attach to a single database
and not to share the entire data folder.

The scenario for creating shared database is as follows:

1. Process a new copy of the database, or just update an existing one by processing
some of its objects on a processing server.
2. Detach new version of the database from the processing server and copy it to a
shared location
3. Detach all front-end servers from the old copy of the database, and then attach then
to a new copy in read-only mode.

Attach\Detach, Read-Only, and
DbStorageLocation

Attach\Detach, Read-Only, and DbStorageLocation all three features tightly integrated.
And we are going to talk about them together. For instance, you cannot mark database as
read-only without detaching and attaching it first.

Detach

Attach and detach functionality is similar to backup and restore functionality; it is the
ability to create an independent copy of a database and then bring it online to Analysis
Services. The difference to a backup operation is that the database detach results in the
database no longer being available to users to query. As a result of the detach operation,
Analysis Services separates all the files that belong to a database being detached into a
single (a database) folder. By default, your database folder is located under the Analysis
Services Data folder. For instance, if you are detaching our sample database, the resulting
folder containing all the FoodMart 2008 files would be: C:\Program Files\Microsoft SQL
Server\MSAS10.MSSQLSERVER\OLAP\Data\FoodMart 2008.0.db . In addition to all your data-
base data and metadata files, you will find one more file in your database folder after