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Microsoft vs VMware on Exchange Virtualization and HA Best Practices

Paul Cunningham — Thu, 11 Nov 2010 09:00:19 +0000

I recently pointed out the difference between Microsoft and VMware guidance on mixing Exchange Server 2010 DAGs with hypervisor HA features. In short, Microsoft clearly states that hypervisor HA features should be disabled for DAG members, while VMware considers it to be an effective solution.

My own view on this hasn’t changed – stick to what is supported, not what is possible.

I’m not a VMware expert so I have no way to dig deeper into whether VMware HA would be a viable or effective solution when mixed with Exchange Server 2010 DAGs. Others around the industry have weighed in from their position of knowledge and it seems that there may be an issue of interpretation of how different hypervisor HA features work.

Which doesn’t change the support position of Microsoft at all.

It seems that Microsoft has been receiving more than a few customer enquiries about this recently which has prompted this statement on the Microsoft Exchange Team blog.

While Microsoft embraces virtualizing Exchange servers because virtualization gives organizations additional choice and deployment flexibility to meet business requirements and lower IT costs, we’re concerned by deployment guidance that doesn’t accurately follow our Exchange best practices and deployment guidelines.

From there the language gets a little stronger (emphasis added by me).

For example, we feel VMware’s misleading guidance represented in their recent “Exchange 2010 on VMware Availability and Recovery Options” document (and accompanying “Exchange 2010 on VMware Best Practices Guide”) puts Exchange customers at risk, and brushes aside important system requirements and supported configurations. Their guidance could also greatly increase the overall cost of managing your Exchange infrastructure.

Microsoft goes on to make their position very clear (emphasis theirs this time).

VMware specifically recommends combining their VMware HA solution with the Exchange application-aware high availability solution, which is an unsupported configuration. It is important to note that VMware’s HA solution only protects from some hardware failures, while the Exchange high availability solution protects against both hardware and application failures (including a process for patching guest virtual machines). It is simply reckless for VMware to recommend customers deploy this configuration, while ignoring important Microsoft system requirements and unsupported scenarios. In addition, VMware also seems to gloss over the fact that combining these HA solutions will result in new storage requirements that increase cost and complexity. Considering that a significant focus of Exchange 2010 is reducing storage costs, promoting a strategy that increases storage costs isn’t consistent with our customers’ requirements.

There is nothing within the material that explains how combining Exchange database availability groups (DAGs) with VMware HA will provide a faster end-user mailbox recovery than using Exchange DAGs alone. Since Exchange HA protects against hardware and application failures, it is hard to imagine how VMware can provide a faster, and simpler solution than Exchange HA alone.

Microsoft does not support combining Exchange high availability (DAGs) with hypervisor-based clustering, high availability, or migration solutions that will move or automatically failover mailbox servers that are members of a DAG between clustered root servers. Microsoft recommends using Exchange DAGs to provide high availability, when deploying the Exchange Mailbox Server role. Because hypervisor HA solutions are not application aware, they cannot adapt to non-hardware failures. Combining these solutions adds complexity and cost, without adding additional high availability. On the other hand, an Exchange high availability solution does detect both hardware and application failures, and will automatically failover to another member server in the DAG, while reducing complexity.

So not only is it unsupported, it may in fact be pointless and more expensive to implement and manage as well.

Like I said earlier I’m no VMware expert, but that makes a lot of sense to me.

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Exchange Server 2010 DAGs and VMware High Availability

Paul Cunningham — Mon, 23 Aug 2010 09:00:13 +0000

If you are planning to deploy Exchange Server 2010 Database Availability Groups, and you virtualize your Exchange environment, then it is important to understand the supported scenarios.

Microsoft makes it very clear in their system requirements for Exchange Server 2010:

Microsoft doesn’t support combining Exchange high availability solutions (database availability groups (DAGs)) with hypervisor-based clustering, high availability, or migration solutions that will move or automatically failover mailbox servers that are members of a DAG between clustered root servers. DAGs are supported in hardware virtualization environments provided that the virtualization environment doesn’t employ clustered root servers, or the clustered root servers have been configured to never failover or automatically move mailbox servers that are members of a DAG to another root server.

In short, DAG members should have any virtualization high availability options disabled.

This is in slight contrast to the advice from VMware themselves:

While the use of database availability groups on top of hypervisor based clustering is not a formerly (sic) supported configuration, internal VMware tests have shown that the two technologies can co-exist and can be a viable solution to ensure maximum recoverability in the case of a host failure.

To paraphrase, it isn’t supported but we think you’ll be fine.

You might get some push back from customers or managers who have been sold on the idea of VMware HA for everything, or who take the line from VMware as implied support for the configuration. But in the real world I prefer to go with what is supported over what is possible.

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Installing VMWare Tools on Windows Server 2008 Core

Paul Cunningham — Thu, 16 Apr 2009 05:24:56 +0000

When installing the VMWare tools on a core install of Windows Server 2008 some people are confused to find that nothing happens after selecting “Install/Upgrade VMWare Tools” from the client window.

Even though the VMWare Tools image mounts to the virtual CD-ROM drive it does not autorun as you would expect in a normal install of Windows Server 2008. However you can still change directory to the virtual CD-ROM and see the VMWare Tools installation files are available.

To install the VMWare Tools you can simply launch setup.exe from the command line.

Follow the installation wizard accepting the default settings. You can also ignore the warnings about the Microsoft Help HTML engine and the version of Internet Explorer.

When the installer has finished you can reboot as normal and the VMWare Tools will now be installed.

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Exchange Server 2007 is now supported for hardware virtualisation

Paul Cunningham — Fri, 22 Aug 2008 10:00:19 +0000

We’ve been virtualising Exchange Server 2007 since it was first released but this week Microsoft has announced their official support policies for virtualised Exchange environments. It is a bit heavy on the Hyper-V but also references the list of support partners for non-Microsoft hardware virtualisation. When I checked this earlier in the week VMWare was a notable absence but today Dugie confirmed for me that they’ve been added to the list, which now stands as follows:

Cisco Systems, Inc.
Citrix Systems, Inc.
Novell, Inc.
Sun Microsystems
Unisys Corp.
Virtual Iron Software
VMware, Inc.

If you’re planning an Exchange Server 2007 deployment using a virtualisation platform be sure to read Microsoft’s recommendations for sizing virtual machines.

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VMWare to release VMWare ESXi for free

Paul Cunningham — Wed, 23 Jul 2008 10:08:45 +0000

I saw Dan’s post on this subject and did a little Googling and lo and behold, VMWare have announced that their ESXi product will be released for free.

I’m no VMWare guy like these guys , but as I understand it ESXi is the skinny little hypervisor (clocking in at 32mb) that lets you run virtual guest operating systems. So you could buy yourself a server with a few cores, lots of RAM, some disk (hey maybe even use iSCSI for storage ) and run lots of virtual servers within that environment.

How can they be releasing something so good for free? Well they’ve done it before, releasing the successor to VMWare GSX Server called VMWare Server for free a few years ago. This was awesome for IT pros who rely on virtualisation to run labs when they are doing training. And now with ESXi we’ll be able to do it even easier (VMWare Server still requires you to install an OS like Windows first, whereas ESXi is the OS – so to speak).

Aside from having done this before, VMWare says the bulk of their revenues come from sales of their Virtual Infrastructure suite (the bits that let you run clusters of ESX servers, do failover of guests between hosts, resource management etc). So basically they can afford to give away the basic bits (run virtual guests on a single host) for free.

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