SQL Server 2005 and higher supports database mirroring, in which the principal server sends, in real-time, blocks of its database log records to the mirror instance which, in the event of failover, can be made available within a few seconds.
PowerDesigner supports database mirroring with endpoints and extensions on the database object.
Creating a Database for Mirroring
To create a database to model database mirroring:
- Right-click the model in the Browser and select Properties.
- On the General tab, click the Create tool to the right of the Database field.
- Click the Mirroring tab and specify any appropriate properties.
Mirroring Properties
You can modify an object's properties from its property sheet. To open a database property sheet, double-click its Browser entry.
The following extended attributes are available on the Mirroring tab:
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Name
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Description
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Enable mirroring
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Enables mirroring for the database.
Scripting name: EnableMirroring
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Partner/ Witness
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Specifies the role that the database will play in the mirroring relationship. You can choose between:
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Partner – the database is either a principal or mirror database.
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Witness – the database acts as a witness to a mirroring relationship. A SET WITNESS clause affects both copies of the database, but can only be specified on the principal server. If a witness is set for a session, a quorum is required to serve the database, regardless of the SAFETY setting.
Scripting names: Partner, Witness
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Options
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Specifies mirroring options for the database. You can choose between:
Scripting name: MirrorOptions
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Server
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For partner mirroring, specifies the server network address of an instance of SQL Server to act as a failover partner in a new database mirroring session.
For witness mirroring, specifies an instance of the Database Engine to act as the witness server for a database mirroring session.
Scripting name: MirrorServer
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Time-out
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[if partner is selected] Specifies the time-out period in seconds. The time-out period is the maximum time that a server instance waits to receive a PING message from another instance in the mirroring session before considering that other instance to be disconnected.
Scripting name: TimeOut
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