Failover Clustering Support (Enterprise Edition Only)
Applies To: Microsoft iSCSI Software Target
The Microsoft iSCSI Software Target 3.3 is a cluster-aware application, and it can be used to provide file and block storage services on failover clusters that run the Windows Server 2008 R2 Enterprise and Windows Storage Server 2008 R2 Enterprise operating systems. This failover cluster support provides redundancy for shared block storage or storage area networks (SANs). This enhances the availability of applications that can be scaled across the cluster nodes.
You implement failover clustering by configuring highly available instances (also known as resource groups) on storage appliances that are part of a failover cluster. Each highly available instance is a collection of resources that run together on a cluster node and fail over as a single unit. You can create new highly available instances, or if you have previously configured any highly available instances, you can use those resource groups. You can use the same resource group to provide high availability for both file sharing and block sharing. For more information about the use of resource groups, see Failover Cluster Management Help.
In an iSCSI-based cluster environment, the iSCSI virtual disk must reside on a shared cluster disk, and an existing iSCSI virtual disk can only be added to an iSCSI target that belongs to the same resource group. Microsoft iSCSI Software Target must be installed on every node in the cluster to provide failover support for iSCSI resources.
Supported failover cluster configurations
Windows Server 2008 R2 and Windows Storage Server 2008 R2 support failover clustering in various configurations. These configurations support increasing levels of redundancy to ensure data availability. Storage appliances running Windows Storage Server 2008 R2 Enterprise can be used in the following failover cluster configurations:
Highly available target, single path: A single initiator computer uses an iSCSI initiator to connect to a failover cluster that contains two or more nodes. The storage appliances are connected to external storage, such as Fibre Channel or iSCSI, to provide a quorum disk and cluster storage.
Highly available target, multipath: A single iSCSI initiator server uses Microsoft Multipath I/O (MPIO) to connect to a failover cluster that contains two or more nodes. The nodes are connected to external storage, such as Fibre Channel or iSCSI, to provide a quorum disk and cluster storage.
Highly available initiators and targets: The initiators are in a highly available failover cluster, which is connected to a failover cluster that contains two or more nodes. A single subnet connects the initiator cluster to the storage appliance cluster. The storage appliances are connected to external storage, such as Fibre Channel or iSCSI, to provide a quorum disk and cluster storage.
Requirements for iSCSI storage failover clustering
You can configure failover clustering to provide high availability for the iSCSI storage provided by Windows Server 2008 R2 or Windows Storage Server 2008 R2. Configuring failover clustering for Windows Server 2008 R2 or Windows Storage Server 2008 R2 is slightly different from configuring failover clustering in Windows Server 2008. These differences are in the requirements that are needed to support the Microsoft iSCSI Software Target 3.3.
Microsoft iSCSI Software Target 3.3 is installed on each node in the failover cluster.
There are no iSCSI targets before the failover cluster is created.
Each node that will participate in the failover cluster passes all cluster validation tests in the Failover Cluster Management console.
The Failover Cluster feature is installed on each node and is configured to use a shared storage back-end such as iSCSI, Fibre Channel, or SAS interconnect.
There is at least one cluster disk listed in Available Storage in the Failover Cluster Management console.
The network adapters are configured to support separate subnets for storage and client access.
Creating a failover cluster
Creating a failover cluster that uses Microsoft iSCSI Software Target requires a modified procedure from typical failover cluster creation. When you create a failover, use the following steps as a guide:
Connect to iSCSI storage: Use Microsoft iSCSI Software Initiator to connect each node in the failover cluster to the iSCSI storage. A failover cluster requires that each node have access to storage for cluster functions and for data storage to provide as a high available resource. .
Create the failover cluster: Use the Failover Cluster Management console to create a new failover cluster.
Install Microsoft iSCSI Software Target: Install Microsoft iSCSI Software Target on each node in the cluster if your failover cluster will provide highly available block storage.
Configure a resource group: Use the Configure a Service or Application Wizard in the Failover Cluster Management console to create a resource group. Resource group names must be unique on a failover cluster.
Create an iSCSI target: Use the Microsoft iSCSI Software Target console to create a new iSCSI target.
Create virtual disks: Use Microsoft iSCSI Software Target to create virtual disks for each target.
Assign an iSCSI initiator: Assign an initiator for each iSCSI target that you create. This link between an initiator and the target prevents other computers from accessing the target.