4.0.0 HP PolyServe Software for Microsoft SQL Server Administration Guide (T5392-96056, March 2010)

• Removes the IP address for the Virtual SQL Server from the original node and then adds it to the
backup node.
• Updates registry keys and then starts SQL Server and SQL Agent on the backup node.
Clients using the IP address of the Virtual SQL Server will now access the databases on the PSFS
filesystem via the SQL instance on the backup node.
After a Virtual SQL Server fails over, by default it remains on the backup node. (Optionally, you can
configure the Virtual SQL Server to automatically fail back to the original node.)
Replication of registry keys
HP PolyServe Software replicates the registry keys for the SQL server from the local machine to a
location on the PSFS filesystem containing the corresponding “master” SQL databases. The replicator
watches the main SQL instance key and, if it changes, persists the key to the shared filesystem.
If a Virtual SQL Server fails over to a backup node, that node reads the keys from the PSFS filesystem
and applies them back before starting SQL services. On failback, after SQL services are stopped on
the backup node, the registry is returned to its original state on that node.
Virtual MSDTC
HP PolyServe Software provides high availability support for Microsoft Distributed Transaction
Coordinator (MS DTC), the transaction manager responsible for coordinating transaction atomicity
across multiple resource managers. A Virtual MSDTC is configured on at least two cluster nodes, with
one node serving as the primary and the other nodes as backups. MS DTC is accessed via the Virtual
MSDTC. If a problem occurs on the primary node, the Virtual MSDTC can fail over to a backup node,
which will continue the MS DTC operations. See Chapter 6 on page 77, for more information about
configuring MS DTC for high availability.
MS DTC can also be managed by a Virtual SQL Server, as in previous releases of this product.
Virtual SSAS
HP PolyServe Software includes high availability support for Microsoft SQL Server 2005/2008
Analysis Services (SSAS) instances, which provide online analytical processing (OLAP) and data
mining features. A Virtual SSAS is configured on at least two cluster nodes, with one node serving as
the primary and the other nodes as backups. SSAS instances are then associated with the Virtual
SSAS. The SSAS instances are accessed via the Virtual SSAS. If a problem occurs on the primary
node, the Virtual SSAS can fail over to a backup node, which will then provide access to the SSAS
instances. See Chapter 7 on page 89, for more information about configuring SSAS for high
availability.
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