Cluster Support (Enterprise Edition Only)
Applies To: Microsoft iSCSI Software Target
This release provides support for failover clustering. This cluster support provides redundancy for shared block storage or storage area networks (SANs), enhancing the availability of applications that can be scaled out across the cluster nodes.
You implement 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 are failed over as a single unit. You have the option of creating new highly available instances (resource groups) 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 the Failover Cluster Management help file.
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. The Microsoft iSCSI Software Target must be installed on every node in the cluster in order to provide failover support for iSCSI resources.
Supported Failover Cluster Configurations
Windows Storage Server 2008 supports failover clustering in various configurations, each supporting increasing levels of redundancy to ensure data availability. Your storage appliances running Windows Storage Server 2008 Enterprise Edition 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 Windows Storage Server 2008 storage appliances. The storage appliances are connected to external storage, such as fiber channel or iSCSI, to provide a quorum disk and cluster storage.
Highly available target, multipath - A single initiator computer uses an iSCSI initiator by using multipath input output (MPIO) to connect to a failover cluster that contains two or more Windows Storage Server 2008 storage appliances. The storage appliances are connected to external storage, such as fiber channel or iSCSI, to provide a quorum disk and cluster storage.
Highly available initiators and targets – In this configuration, the initiators are in a highly available failover cluster connected to a failover cluster that contains two or more Windows Storage Server 2008 storage appliances. The storage appliances are connected to external storage, such as fiber channel or iSCSI, to provide a quorum disk and cluster storage. There is a single network subnet connecting the initiator cluster to the storage appliance cluster.
Creating a failover cluster with your Windows Storage Server 2008 appliance by using the Microsoft iSCSI Software Target requires a modified procedure from the typical failover cluster. When you create a failover cluster with Windows Storage Server 2008, use the following steps as a guide:
Connect to iSCSI storage – A failover cluster requires that each node have access to storage both for cluster functions and for data storage to provide as a high available resource. If using iSCSI, use the iSCSI Initiator included with Windows Storage Server 2008 to connect each node to the iSCSI storage.
Create the failover cluster – Use the Failover Cluster Management console to create a new failover cluster.
Install the Microsoft iSCSI Software Target – If your failover cluster will provide highly available block storage, you will need to install the Microsoft iSCSI Software Target. Install the Microsoft iSCSI Software Target on each node in the cluster.
Define the Windows Firewall exceptions – Most of the exceptions that are required by failover clustering will be added automatically when you install the Failover Cluster feature. However, some exceptions for the Microsoft iSCSI Software Target must be added manually.
Configure a resource group – You can use the Failover Cluster Management console to create a resource group by using the Configure a Service or Application wizard. 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 the Microsoft iSCSI Software Target to create virtual disks for each target.
Assign an iSCSI initiator – Assign an initiator for each iSCSI target you create. The assignment creates a link between an initiator and a target that prevent other computers from accessing the target.