A failover cluster must meet certain requirements for hardware, software, and network infrastructure, and it requires the administrator to use an account with the appropriate domain permissions. The following sections provide information about these requirements.
- Hardware requirements for a failover
- Software requirements for a failover
- Network infrastructure and domain
account requirements for a failover cluster
For additional information about hardware compatibility for Windows Server 2008 R2, see http://go.microsoft.com/fwlink/?LinkId=139145.
Hardware requirements for a failover cluster
You need the following hardware in a failover cluster:
- Servers: We recommend that you use a
set of matching computers that contain the same or similar
Microsoft supports a failover cluster solution only if all the hardware components are marked as "Certified for Windows Server 2008 R2." In addition, the complete configuration (servers, network, and storage) must pass all tests in the Validate a Configuration Wizard, which is included in the Failover Cluster Manager snap-in.
For information about the maximum number of servers that you can have in a failover cluster, see http://go.microsoft.com/fwlink/?LinkId=139146.
- Network adapters and cable (for network
communication): The network hardware, like other components in
the failover cluster solution, must be marked as "Certified for
Windows Server 2008 R2." If you use iSCSI, your network
adapters should be dedicated to either network communication or
iSCSI, not both.
In the network infrastructure that connects your cluster nodes, avoid having single points of failure. There are multiple ways of accomplishing this. You can connect your cluster nodes by multiple, distinct networks. Alternatively, you can connect your cluster nodes with one network that is constructed with teamed network adapters, redundant switches, redundant routers, or similar hardware that removes single points of failure.
If you connect cluster nodes with a single network, the network will pass the redundancy requirement in the Validate a Configuration Wizard. However, the report from the wizard will include a warning that the network should not have single points of failure.
- Device controllers or appropriate adapters
for the storage:
- For Serial Attached SCSI or Fibre
Channel: If you are using Serial Attached SCSI or Fibre
Channel, in all clustered servers, the mass-storage device
controllers that are dedicated to the cluster storage should be
identical. They should also use the same firmware version.
With Windows Server 2008 R2, you cannot use parallel SCSI to connect the storage to the clustered servers. This was also true for Windows Server 2008.
- For iSCSI: If you are using iSCSI,
each clustered server should have one or more network adapters or
host bus adapters that are dedicated to the cluster storage. The
network you use for iSCSI should not be used for network
communication. In all clustered servers, the network adapters you
use to connect to the iSCSI storage target should be identical, and
we recommend that you use Gigabit Ethernet or higher.
For iSCSI, you cannot use teamed network adapters, because they are not supported with iSCSI.
For more information about iSCSI, see the iSCSI FAQ on the Microsoft Web site (http://go.microsoft.com/fwlink/?LinkId=61375).
- For Serial Attached SCSI or Fibre Channel: If you are using Serial Attached SCSI or Fibre Channel, in all clustered servers, the mass-storage device controllers that are dedicated to the cluster storage should be identical. They should also use the same firmware version.
- Storage: You must use shared storage
that is compatible with Windows Server 2008 R2.
In most cases, the storage should contain multiple, separate disks (LUNs) that are configured at the hardware level. For some clusters, one disk functions as the disk witness (described at the end of this subsection). Other disks contain the files required for the clustered services or applications. Storage requirements include the following:
- To use the native disk support included in
failover clustering, use basic disks, not dynamic disks.
- We recommend that you format the partitions
with NTFS. If you have a disk witness or use Cluster Shared
Volumes, the partition for each of those must be NTFS.
For Cluster Shared Volumes, there are no special requirements other than the requirement for NTFS. For more information about Cluster Shared Volumes, see Understanding Cluster Shared Volumes in a Failover Cluster.
- For the partition style of the disk, you can
use either master boot record (MBR) or GUID partition table
- To use the native disk support included in failover clustering, use basic disks, not dynamic disks.
Deploying storage area networks with failover clusters
When deploying a storage area network (SAN) with a failover cluster, follow these guidelines:
- Confirm compatibility of the storage:
Confirm with manufacturers and vendors that the storage, including
drivers, firmware, and software used for the storage, are
compatible with failover clusters in Windows
Server 2008 R2.
Storage that was compatible with server clusters in Windows Server 2003 might not be compatible with failover clusters in Windows Server 2008 R2. Contact your vendor to ensure that your storage is compatible with failover clusters in Windows Server 2008 R2.
- Improvements in failover clusters (as
compared to server clusters in Windows Server 2003) require
that the storage respond correctly to specific SCSI commands. To
confirm that your storage is compatible, run the Validate a
Configuration Wizard. In addition, you can contact the storage
- The miniport driver used for the storage must
work with the Microsoft Storport storage driver.
- Improvements in failover clusters (as compared to server clusters in Windows Server 2003) require that the storage respond correctly to specific SCSI commands. To confirm that your storage is compatible, run the Validate a Configuration Wizard. In addition, you can contact the storage vendor.
- Isolate storage devices, one cluster per
device: Servers from different clusters must not be able to
access the same storage devices. In most cases, a LUN used for one
set of cluster servers should be isolated from all other servers
through LUN masking or zoning.
- Consider using multipath I/O software:
In a highly available storage fabric, you can deploy failover
clusters with multiple host bus adapters by using multipath I/O
software. This provides the highest level of redundancy and
availability. For Windows Server 2008 R2, your multipath
solution must be based on Microsoft Multipath I/O (MPIO). Your
hardware vendor will usually supply an MPIO device-specific module
(DSM) for your hardware, although Windows Server 2008 R2
includes one or more DSMs as part of the operating system.
Host bus adapters and multipath I/O software can be very version sensitive. If you are implementing a multipath solution for your cluster, you should work closely with your hardware vendor to choose the correct adapters, firmware, and software for Windows Server 2008 R2.
Software requirements for a failover cluster
All the servers in a failover cluster must either run the x64-based version or the Itanium architecture-based version of Windows Server 2008 R2 (nodes within a single failover cluster cannot run different versions).
All the servers should have the same software updates (patches) and service packs.
The Failover Clustering feature is included in server products such as Windows Server 2008 R2 Enterprise and Windows Server 2008 R2 Datacenter. The Failover Clustering feature is not included in Windows Server 2008 R2 Standard or Windows Web Server 2008 R2.
Network infrastructure and domain account requirements for a failover cluster
You will need the following network infrastructure for a failover cluster and an administrative account with the following domain permissions:
- Network settings and IP addresses:
When you use identical network adapters for a network, also use
identical communication settings on those adapters (for example,
Speed, Duplex Mode, Flow Control, and Media Type). Also, compare
settings between the network adapter and the switch it connects to
and make sure that no settings are in conflict.
If you have private networks that are not routed to the rest of your network infrastructure, ensure that each of these private networks uses a unique subnet. This is necessary even if you give each network adapter a unique IP address. For example, if you have two cluster nodes in a central office that uses one physical network, and two more nodes in a branch office that uses a separate physical network, do not specify 10.0.0.0/24 for both networks, even if you give each adapter a unique IP address.
For more information about the network adapters, see Hardware Requirements for a Failover Cluster, earlier in this topic.
- DNS: The servers in the cluster must
be using Domain Name System (DNS) for name resolution. The DNS
dynamic update protocol can be used.
- Domain role: All servers in the
cluster must be in the same Active Directory domain. As a best
practice, all clustered servers should have the same domain role
(either member server or domain controller). The recommended role
is member server.
- Domain controllers: We recommend that
your clustered servers be member servers. If they are, other
servers will be the domain controllers in the domain that contains
your failover cluster.
- Clients: There are no specific
requirements for clients, other than the obvious requirements for
connectivity and compatibility: the clients must be able to connect
to the clustered servers, and they must run software that is
compatible with the services offered by the clustered servers.
- Account for administering the cluster:
When you first create a cluster or add servers to it, you must be
logged on to the domain with an account that has administrator
rights and permissions on all servers in that cluster. The account
does not need to be a Domain Admins account—it can be a
Domain Users account that is in the Administrators group on
each clustered server. In addition, if the account is not a
Domain Admins account, the account (or the group that the
account is a member of) must be delegated Create Computer
Objects permission in the domain. For more information, see
Failover Cluster Step-by-Step Guide: Configuring Accounts in Active
There is a change in the way the Cluster service runs in Windows Server 2008 R2, as compared to Windows Server 2003. In Windows Server 2008 R2, there is no Cluster service account. Instead, the Cluster service automatically runs in a special context that provides the specific permissions and privileges necessary for the service (similar to the local system context, but with reduced privileges).
- Validating a Failover
- Overview of Failover
- For information about hardware compatibility
for Windows Server 2008 R2, see http://go.microsoft.com/fwlink/?LinkId=139145.
- For design and deployment information for
failover clusters, see http://go.microsoft.com/fwlink/?LinkId=137832.