3.6.0 Matrix Server Upgrade Guide (5697-7085, February 2008)

Chapter 2: Overview 8

a two-node cluster, you would declare one node to be the primary for the

instance and the second node to be the backup. The high-availability

engine provided with MxDB for SQL Server would then create a profile

for each node.

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. With the Primary-Backup architecture, also called

the “N model,” the total number of profiles for a virtualized SQL instance

is equal to the number of nodes participating in the Virtual SQL Server. If

the primary node goes down, the high-availability engine provided with

MxDB for SQL Server will mount the profile from that node onto the

backup node and then bring up the SQL instance on that node. Although

this architecture provides high-availability, it can be susceptible to

duplicate registry issues.

The new Active-Passive architecture provided with the 3.6 release is very

flexible and highly resistant to the duplicate registry issue. This new

architecture provides an “N+1 model.” For a two-node cluster, there are

now 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).

Using the Upgrade Tool

The upgrade tool prepares a cluster running MxDB for SQL Server 3.4 for

a successful upgrade to the 3.6 release. The tool corrects any duplicate

registry entries and creates a 3.6 local profile (the “N” profile) for the

primary node. This local primary profile is not used by the SQL engine

provided with MxDB for SQL Server 3.4 and does not affect the working

behavior of the 3.4 cluster in any way.

To create the 3.6 local profile for the primary node, the upgrade tool

requires that you specify a valid backup node that can be used to copy the

SQL data and recreate a local registry for the primary node.