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

6 Configure Virtual MSDTC
The Microsoft Distributed Transaction Coordinator (MS DTC) is the transaction manager responsible
for coordinating transaction atomicity across multiple resource managers. It ensures that an update
of data (work) is either committed or rolled back on all servers that are participating in the transaction.
This chapter describes how to configure MS DTC for high availability.
Overview
At least two cluster nodes are required to configure MS DTC for high availability. In this configuration,
MS DTC is accessed via a virtual host (a Virtual MSDTC). One cluster node is primary for the Virtual
MSDTC and the other nodes are backup. An MSDTC Service monitor is associated with the Virtual
MSDTC. If the monitor detects that the MS DTC NT service is down or that the MS DTC data path is
not available, the Virtual MSDTC can fail over to a backup node, which will continue the MS DTC
operations.
When configuring nodes to host the Virtual MSDTC, you should be aware of the following:
• Virtual SQL Servers and Virtual SSAS Servers cannot be hosted on the nodes that are hosting a
Virtual MSDTC. The Virtual SQL Servers and Virtual SASS Servers must connect remotely to the
Virtual MSDTC service.
• The Virtual MSDTC nodes must use the same architecture (either 32-bit or 64-bit).
• The Virtual MSDTC nodes do not need to be dedicated to MS DTC operations and can be used
for other activities or applications that do not rely on the local MS DTC service.
• The Virtual MSDTC nodes can be configured as a separate cluster or they can be included in a
larger cluster.
• The MS DTC transaction logs are stored on a shared PSFS filesystem where they can be accessed
by both nodes.
DNS requirement for the Virtual MSDTC
A DNS entry must exist for the Virtual MSDTC/IP address. The entry must include an A record and a
PTR record for forward and reverse lookup. Windows authentication may fail if these records do not
exist.
DTC transaction statistics
When a Virtual MSDTC fails over to another node, the DTC transaction statistics are not carried over
to the new node. Instead, the statistics are reset to zero.
Create a Virtual MSDTC
To create a Virtual MSDTC, start the PolyServe Management Console and then select Matrix > Add
> Add Virtual MSDTC. The Add Virtual MSDTC window appears.
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