What NAS can do for Microsoft Exchange
Microsoft recently announced support for using NAS
devices for Microsoft Exchange if the NAS devices were built on Windows Storage Server 2003 (WSS03) and has gone through the Microsoft qualification process.
This is a significant development that has great potential for customers and implications on other technologies.
The big advantage for customers is that they can use a NAS device for Exchange which is much simpler to administer than attaching a block storage system in a Storage Area Network (SAN). For the typical customer that has Exchange and wants to use a consolidated
storage solution external to the server, this presents a great option that requires less administrative efforts than the alternatives. This translates to a lower cost of ownership and fits better into environments that don't have specific storage administrators.
The implication on other technologies is in regards to the typical customer in that they may not need to implement a Storage Area Network. The most popular SAN
technology is Fibre Channel
but there is focus on the small to mid-size business (SMB) market with iSCSI
as the SAN implementation over IP
(Internet Protocol). Customers will now have a much simpler option for Exchange with the NAS support.
But, there are some things to be aware of when considering NAS for Exchange. Microsoft was very clear in that the Microsoft support for Exchange on NAS requires that NAS device be built on a WSS03 base and qualified. For this support, a Feature Pack has to be installed on the WSS03-based NAS device. This announcement by Microsoft does not state that Exchange will not work on NAS devices that are not based on WSS03 (most other vendors use a proprietary NAS implementation). It just says that Microsoft will not provide support for it.
This begs the question "why not?" and "what is the implication?" The reason is that Microsoft believes that to adequately support Exchange, Microsoft has to have visibility into the implementation details of the file system. If the NAS device is based on WSS03, they would have that regardless of whether NTFS
was used as the file system for the NAS device. With a NAS device not based on WSS03, Microsoft could not "see" into the details of the file system on the NAS device. The NAS device implements a remote file system which is used by the client which in this case is an Exchange server. The remote file system is accessed by redirecting a local file system access to the NAS device using the CIFS protocol
Does this mean other NAS devices will not work for Exchange? No. They may work just fine and may have other attributes that might be desirable to customers. If there is a problem that a customer needs support to resolve, a call to Microsoft Exchange support might resolve the problem but if it is unclear, Microsoft will probably refer the customer to the support team for the NAS vendor that is not WSS03-based. This creates some concern with some customers.
So, should a customer use a non-WSS03 based NAS device? The answer is one of judgment based on understanding and trust. Does the non WSS03-based NAS vendor support Exchange? How good is their support if Microsoft refers the customer to the NAS vendor? Do you trust the NAS vendor and their support for resolution of the problem in the mission-critical application Exchange? These are tough questions that need to be asked. Part of becoming comfortable with the answers may include getting some type of guarantee from the vendor.
Using NAS for Exchange is a great answer for many customer problems. The advantages in administration are just too great to ignore. The choices of NAS devices have to be weighed carefully -- qualified WSS03-based NAS device or one that is not. In the end it has to be a choice with which the customer is comfortable. It is unlikely that Microsoft will change their decision on qualification of NAS devices in the near term.