Database Reference
In-Depth Information
However, as a best practice many installations out there may not use 1433 as a default port
for SQL Server instance, in addition to using Microsoft SQL Server JDBC driver (see
http://
msdn.microsoft.com/en-us/library/ms378749.aspx
). So when a named port
is defined with a firewall exception and a JDBC is used, then the automatic failover is not
supported. To provide extra availability support and standby for the application, database
mirroring can be used on a failover clustering instance. In such cases, the principal server
and mirror server both reside on clusters between the data centers. The principal database
will be hosted on an active node of one cluster and the mirror database will be hosted on an
active node of another cluster. It is also possible to establish a mirroring session between the
clustered and un-clustered instances. However, the availability for applications is dependent
on the database mirroring operating mode. In this recipe, we will go through the process of
managing database mirroring in a failover clustering environment.
Getting ready
All the prerequisites to install failover clustering can be referred to in the
Installing
and
configuring
failover
cluster
services
recipe and for database mirroring, refer to the
Implementing
database
mirroring
features
and
performance
enhancements
recipe.
To manage database mirroring in a clustered environment, the selected operating mode for
mirroring is significant. SQL Server 2008 R2 has changed the operating modes for database
mirroring, and they are:
F
High Performance
F
High Safety with automatic failover
F
High Safety without automatic failover
How to do it...
The following steps are required to set up the database mirroring partners and failover cluster
nodes in a clustered environment, which is an essential task in managing database mirroring
in a failover cluster environment.
1.
On the database mirroring pair, when the high-safety mode with automatic failover is
used, it is ideal to set up the mirroring between two cluster environments (in different
data centers) for maximum availability. The witness instance can reside on the active
node or on an un-clustered machine within the same network.
2.
On the database mirroring pair, when the high-performance mode is used, it is ideal
to host the principal server on the failover clustered instance of a cluster and place
the mirror server on an un-clustered server outside of the cluster environment.
3.
It is highly recommended that you change the default value
10
for database mirroring
PARTNER
TIMEOUT
to a higher number as follows:
ALTER DATABASE AdventureWorks2008R2 SET PARTNER TIMEOUT 300
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