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17 Juli 2012

Using Mirroring and Snapshots for Reporting Servers

SQL Server 2005 provides a technology called snapshots
that provides a read-only copy of an OLTP database.
Its easy to configure and deploy.

The main issue is that by itself, a snapshot is on the local SQL Server as the production OLTP database.
Hence, even though reporting users and OLTP users are on separate databases,
they still share the same SQL Server instance memory, CPU, and probably disk subsystem.

Mirroring fixes this contention issue of OLTP and reporting on the same server.
By itself, users cannot run queries against a mirror database because its in a state of recovery.
The solution is for you to snapshot copies off the mirror.
These snapshots are read-only and let users access them directly for reporting.
Whats more, there is also the flexibility of having multiple snapshots of the same database.
This is seen in Figure 27-31.







Source:
Microsoft SQL 2005 Administrator's Companion,
Chapter 27 - Log Shipping and Database Mirroring
Part VI - High Availability
Page 918