There is a growing movement in the industry to encourage Microsoft to modify its position on the suitability and support of non-SMB 3.0-based Network Attached Storage volumes for hosting Exchange Server data files. This movement is in the form of a petition (Support for Exchange Databases running within VMDKs on NFS datastores) posted and signed by a number of Exchange, Storage and Virtualization professionals from various groups and organizations. VMware is not an official co-signer of this petition.
VMware has received a number of inquiries from our customers and partners about this movement, and the following is our position.
Microsoft Exchange Server is a third-party application that is very suitable for virtualization and is demonstrably virtualization-friendly. Microsoft Exchange Server is one of the most common applications our customers run on the VMware vSphere platform. Microsoft Exchange Server customers are subject to the dictates and support statements as published and enforced by Microsoft. This is not different for any other third-party application vendor.
At VMware, our main objective is to ensure that we enable our customers to run the application of their choice on the vSphere platform while remaining in compliance with the application vendor’s requirements. This is why we strive to ensure that our application-specific technical best practices guidance incorporate the relevant requirements specified by the applicable third-party application vendor.
We wish to point out that, although the above-referenced petition specifically mentions “VMDK”, Microsoft’s support (or lack thereof) for file-level storage architecture for Exchange Server data is not specific to “VMDK”. We would like to draw your attention to the relevant portion of Microsoft’s support statement about this restriction to dispel this possible confusion:
The storage used by the Exchange guest machine for storage of Exchange data (for example, mailbox databases and transport queues) can be virtual storage of a fixed size (for example, fixed virtual hard disks (VHDs) in a Hyper-V environment), SCSI pass-through storage, or Internet SCSI (iSCSI) storage. Pass-through storage is storage that’s configured at the host level and dedicated to one guest machine. All storage used by an Exchange guest machine for storage of Exchange data must be block-level storage because Exchange 2013 doesn’t support the use of network attached storage (NAS) volumes, other than in the SMB 3.0 scenario outlined later in this topic. Also, NAS storage that’s presented to the guest as block-level storage via the hypervisor isn’t supported. – Exchange 2013 Virtualization
Our guidance on this topic is clearly documented in our Microsoft Exchange 2013 on VMware Best Practices Guide (page 16, section 2.3.4), which states as follows:
Although VMware testing has shown that NAS attached virtual disks perform very well for Exchange workloads, Microsoft does not currently support accessing Exchange data (mailbox databases, transport queue, and logs) stored on network attached storage. This includes accessing Exchange data using a UNC path from within the guest operating system, as well as virtual machines with VMDK files located on NFS attached storage.
VMware is unaware of any technical challenge inhibiting the use of NAS-based storage for Exchange data files. However, we are deferring all support positions and statements around this topic to Microsoft. Our primary goal is to ensure that our customers can successfully run their application of choice on the VMware vSphere platform while remaining in compliance with the application vendor’s support requirements. We will continue to work with all third party vendors through the appropriate channels to achieve resolutions that are beneficial to our mutual customers and partners.