This blog discusses running a Windows Server Failover Cluster (WSFC) in a Virtual Machine (VM) on top of a VMware host.  Running a cluster in a virtualized environment is commonly referred to as "Guest Clustering".  Guest Clustering enables health monitoring of applications running within a VM, as well as application mobility to allow applications to failover from within one VM to another (for example, to allow patching the guest operating system).  It is supported by Microsoft to run Failover Clustering in a virtualized environment; however the support policy varies for different guest OS versions.

Windows NT Server 4.0 / Windows 2000 Server

It is not supported by Microsoft to run a Guest Cluster with the Microsoft Cluster Service (MSCS) on Windows NT Server 4.0 or Windows 2000 Server in any virtualized environment.

Windows Server 2003

For a cluster solution to be supported by Microsoft it must be a tested solution which has been qualified and verified to function properly with the Failover Clustering (or MSCS) feature.  The full Windows Server 2003 cluster support policy is documented here:  http://support.microsoft.com/kb/309395.

When a cluster solution has been qualified it will receive a 'Designed for Microsoft® Windows® Server 2003' logo and be listed on the Windows Server Catalog under "Cluster Solutions" at the following site: http://www.windowsservercatalog.com/.

Two separate VMware configurations have received a logo and are supported in Windows Server 2003 with vSphere 4.0 and EMC storage.  One configuration is with EMC V-Max storage and the other with EMC CLARiiON CX4 storage.  Details are listed here:

·         http://www.windowsservercatalog.com/item.aspx?idItem=3fe95a9f-0fb0-f22f-3a41-71c3c7e7c359&bCatID=1291

·         http://www.windowsservercatalog.com/item.aspx?idItem=91a18b7b-777a-fdaf-69ca-c3a081085d49&bCatID=1291 

These are the only two supported Windows Server 2003 guest clustering configurations.  The Windows Server 2003 cluster logo program stopped accepting new submissions as of 12/31/09, so no additional configurations will be added in the future.

Windows Server 2008 & Windows Server 2008 R2

The Microsoft support policy for Failover Clustering radically changed with Windows Server 2008 to become much more flexible.  In order for a solution to be supported by Microsoft all individual components must have a Windows Server logo, and the solution must pass the cluster “Validate a Configuration…” tests.  It is supported by Microsoft to run Windows Server 2008 and Windows Server 2008 R2 as a guest cluster.  The full support policy is documented here: http://technet.microsoft.com/en-us/library/cc732035(WS.10).aspx

In particular see the "Virtualized servers" section here: http://technet.microsoft.com/en-us/library/cc732035(WS.10).aspx#BKMK_validation_scenarios 

VMware Considerations

VMware has a Knowledge Base article titled “Microsoft Cluster Service (MSCS) support on ESX” which outlines additional support considerations: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004617. 

It is recommended to also review the VMware support policies which have additional considerations.

Some points of consideration:

·         Windows Server 2008 guest clustering requires vSphere 4.0 or higher

·         Windows Server 2008 R2 guest clustering requires vSphere 4.0 Update 1 or higher

·         Guest Clustering with VMware HA requires vSphere 4.1

·         It is not supported to deploy guest clustering with iSCSI, FCoE, and NFS disks

·         It is not supported to deploy guest clustering  in conjunction with VMware Fault Tolerance

·         It is not supported to vMotion a VM that is part of a guest cluster

Please review the "vSphere MSCS Setup Limitations" section in the documentation linked in the VMware KB above for VMware’s complete and authoritative list of configuration restrictions.

Guest Clustering Support Matrix Summary

Thanks!
Elden Christensen
Senior Program Manager Lead
Clustering & High-Availability
Microsoft

Every day this week the Clustering & High-Availability is writing about some of the top questions we get about Network Load Balancing (NLB) in Windows Server 2008 R2.  We hope you find these helpful!

·         Monday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040072.aspx

·         Tuesday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx

·         Wednesday: http://blogs.msdn.com/b/clustering/archive/2010/07/21/10041067.aspx

·         Thursday: http://blogs.msdn.com/b/clustering/archive/2010/07/22/10041612.aspx

Gary Jackman

Software Test Engineer

Network Load Balancing

Microsoft

Does NLB detect the health or availability of the application it is directing traffic to?

No, for simplicity, NLB is designed to be unaware of any application being hosted on the cluster.  For monitoring application health you will need to use a SCOM Management Pack, 3^rd party tool, or write your own monitoring tool that checks your application and controls NLB appropriately.

Refer to nlbmon.vbs for an example of a custom management utility.  While it does not adjust the node weights, it does stop and start NLB on the nodes based on workload health.  More information: http://msdn.microsoft.com/en-us/library/cc307934(VS.85).aspx

We added health monitoring capability in the SCOM Management Pack specifically for IIS via an IIS-NLB integrated MP. Here is some information on that:

·         http://blogs.msdn.com/clustering/archive/2008/06/24/8648702.aspx

·         http://blogs.msdn.com/clustering/archive/2009/04/28/9572859.aspx

·         http://www.microsoft.com/downloads/details.aspx?FamilyId=78D8C93A-BAE6-4C5D-90AF-B0BF2CE12998&displaylang=en&displaylang=en

Does NLB support multi-homed web servers?

Yes.  You can bind multiple IP addresses to multiple virtual web sites and still use NLB to load balance traffic between them.  Refer to the port rule question on Wednesday’s FAQ for more information.

Every day this week the Clustering & High-Availability is writing about some of the top questions we get about Network Load Balancing (NLB) in Windows Server 2008 R2.  We hope you find these helpful!

·         Monday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040072.aspx

·         Tuesday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx

·         Wednesday: http://blogs.msdn.com/b/clustering/archive/2010/07/21/10041067.aspx

Gary Jackman

Software Test Engineer

Network Load Balancing

Microsoft

Which applications work with NLB?

Since NLB works at the TCP/IP layer, in theory it can work with any TCP or UDP based application. However, depending on the application’s requirement to maintain state or consistency of data, some work better with NLB than others.  Examples of common applications that work well with NLB include: HTTP & HTTPS (web traffic), FTP (file downloads), POP3/SMTP (email), Terminal Services, and Streaming Media.

Other services such as VPN, NAT and IPv6 technologies can also be load balanced.  It is recommended that NLB be configured to use Bi-Directional Affinity (BDA) for these scenarios.  For these scenarios it is recommended to use ISA or DirectAccess for configuring BDA.  More information about BDA is available here: http://technet.microsoft.com/en-us/library/dd364013(WS.10).aspx.

Does NLB provide performance-based load balancing?

No, not directly.  NLB uses a hash algorithm to determine which host a request should be serviced by.  While NLB can facilitate performance-based load balancing, other solutions are required to orchestrate it.   

For example, some people scale-up or scale-down the number of nodes to meet their needs, or they need to change the Load Weight of the port rule to allow some nodes to handle less traffic than others.  This is accomplished by creating a monitoring application that monitors traffic on each node and then takes the appropriate action by automatically changing the Load Weight for a port rule.

Every day this week the Clustering & High-Availability is writing about some of the top questions we get about Network Load Balancing (NLB) in Windows Server 2008 R2.  We hope you find these helpful!

·         Monday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040072.aspx

·         Tuesday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx

Gary Jackman

Software Test Engineer

Network Load Balancing

Microsoft

Can I run mixed clusters containing both physical servers and VMs as NLB nodes?

Yes.  However, all servers and Virtual Machines (VMs) must be on the same VLAN and IP subnet.

What is a port rule?

A port rule is a set of parameters which NLB uses to load balance traffic.  It determines how each port’s NLB network traffic is handled.  The default port rule is defined as:

Depending on the deployment requirements, the user can define port rule per application, or per service which is being load balanced.

For example, if you had a web service that hosted both stateless HTTP (port 80) and HTTPS (port 443) you would want to configure two port rules.

Alternatively if you had a web service had both stateful and stateless HTTP, as well as HTTPS, you could configure three port rules and assign a VIP to the port rules.

In the following example, three VIPs are required.

·         VIP1 belongs to the web service that hosts the stateful HTTP

·         VIP2 belongs to the web service that hosts the stateless HTTP

·         For HTTPS you don’t need to assign two separate VIPs as the ALL will apply to all VIPs

It should be noted that the three port rule only cover 80 and 443.  Any other traffic destined to the cluster VIP will still be handed, but only by the default host.  For example, if a user attempted to FTP to the cluster VIP and FTP was enabled, the default host will be the only host which accepts the connections.

More information about creating and configuring port rules: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx

Microsoft has announced the availability of the Hyper-V Linux Integration Services for Linux Version 2.1. This release marks yet another milestone in providing a comprehensive virtualization platform to our customers. Customers who have a heterogeneous operating system environment desire their virtualization platform to provide support for all operating systems that they have in their datacenters. Microsoft has supported Linux as a guest operating system on MS Virtualization platform from the days of Virtual Server and continue to enhance our support in that regard.

The following features are included in the 2.1 release:

http://www.youtube.com/watch?v=udhd9fmOdCs