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

1 Introduction
HP PolyServe Software for Microsoft SQL Server (HP PolyServe Software) provides high availability
for SQL Server databases located on PSFS cluster filesystems. High availability support is also provided
for MS DTC and Microsoft SQL Server 2005/2008 Analysis Services.
Virtual SQL Servers
HP PolyServe Software uses Virtual SQL Servers to provide failover support and high availability. A
Virtual SQL Server “virtualizes” the network name and IP address associated with a particular SQL
Server/Instance. That is, rather than using the network name and IP address of an actual server, a
Virtual SQL Server is created and assigned a unique name/IP-address pair. Up to 16 SQL instances
can be associated with each Virtual SQL Server.
Clients access the databases associated with an instance via the Virtual SQL Server name or IP address;
they do not need to know which node is running the SQL instance.
When you configure a Virtual SQL Server, you will need to specify an active, or primary, node and
one or more passive, or backup, nodes. The SQL instances associated with the Virtual SQL Server
must be installed on all of these nodes. The Virtual SQL Server is active on the primary node, and
SQL database requests are serviced from there. On failure, the ClusterPulse process (provided with
Matrix Server) will fail over, or migrate, the Virtual SQL Server to one of the designated backup
servers, where it will continue to provide access to the same PSFS filesystem data under the same
name/IP-address pair.
Active-Passive architecture
HP PolyServe Software uses an Active-Passive architecture for high-availability. For example, when
you virtualize a SQL server instance in a two-node cluster, you declare one node to be the active, or
primary, node for the instance and the second node to be the backup. The high-availability engine
provided with HP PolyServe Software for Microsoft SQL Server then creates the appropriate profiles
for the virtualized instance.
A profile is a container consisting of the SQL data (that is, databases and logs) and the corresponding
registry setting necessary for starting an instance of SQL Server. The Active-Passive architecture uses
an “N+1” model in which there is a local profile (an “N” profile”) for each node participating in the
Virtual SQL Server plus a cluster profile (the “+” profile) that runs on the active node for the Virtual
SQL Server.
For example, in a two-node cluster there are three profiles: the two local profiles (N) and a clustered
profile (+1). The clustered profile can move around the cluster, and when mounted on a node, it turns
the state of the node from passive to active. At any one point in time, the node running with the
clustered profile (the “+1” profile) is the active node and all other nodes are passive (that is, running
with their local “N” profiles).
On the PolyServe Management Console, the active node is specified as the primary node and the
passive nodes are specified as backup nodes. Throughout this guide, the primary and backup
designations are used to refer to the active and passive nodes.
HP PolyServe Software for Microsoft SQL Server administration guide 9