Storage relief in sight for Exchange users

IT executives who have married network-attached storage appliances and Microsoft Exchange server - despite Microsoft Corp.'s refusal to support the combination - may see the software giant ease its stance in the coming weeks with the help of a third party.

The union of the two technologies has attracted large companies using Exchange 5.5 because it lets them bypass what they say is a weak Exchange database, to support more users per server, provide users with more space to store e-mail, and have an agile back-up and recovery mechanism.

But Microsoft says it will not support the configuration because it can cause corruption in Exchange databases and degrade the performance of the server.

The company says the problem is even more pronounced in Exchange 2000 than in 5.5. Therefore, it does not support Exchange with any NAS device, which redirects data onto an IP network and into a separate storage system. Microsoft recommends a storage-area network (SAN), or so-called direct-attached storage, for users who want to create a massive information store for Exchange.

To fill the support gap, NAS vendor Network Appliance Inc. says it has nearly completed development of technology that makes its NAS look like direct-attached storage and satisfies Microsoft's concerns, according to Ray Villeneuve, Network Appliance vice president of strategic marketing. He would not offer details.

"It will be an upgrade path for our customers going from Exchange 5.5 to 2000," he says.

It may be the answer for IT executives who say SANs are more than they want and that the combination of NAS and Exchange would make their lives easier.

"We can recover a lot faster with the NAS than we can using Microsoft support," says John Witham, senior data network engineer for Takeda Pharmaceuticals North America.

Witham, who does not use Microsoft support services, has been running Exchange 5.5 and a Network Appliance NAS device for more than a year without problem. He particularly likes the SnapManager feature, which lets him take snapshots of the Exchange data and use it for backup. He also runs a SAN, but that supports database applications.

Witham has not tested his configuration with Exchange 2000. "If we go to 2000 we may be forced to use a SAN. I'd rather not, but if we can't make the NAS work then we will have to try something else."

Bad marriage

Microsoft says the NAS/Exchange 2000 marriage is a bad one because Exchange 2000 has an Installable File System (IFS) that runs in kernel mode. NAS devices, such as those from Network Appliance, also use an IFS.

"If you have two Installable File Systems at the kernel, that can cause corruption," says David Siroky, product manager for Exchange. But he says if the NAS technology was to change and be implemented in another way, Microsoft could offer support for Exchange connected to a NAS device.

Observers say one reason Microsoft won't support NAS now is that Exchange is complex enough without attaching another technology.

"I think there will come a day when Exchange is fed via NAS, but for now Microsoft is just trying to keep people from blowing up the best way it can," says Steve Duplessie, an analyst with Enterprise Storage Group.

Scott Waters, technical manager at the U.S. Army HQ Soldier and Biological Chemical Command in Maryland, is setting up a NAS for Exchange on the recommendation of management, but he would prefer a SAN because it is supported by Microsoft.

"We are spending up to US$100,000 on support [for Exchange], and by putting Exchange on a NAS we are throwing that money away on something that is not supported," he says.

However, he says he can't argue with the end result of the Exchange/NAS combination. He will be able to reduce the number of Exchange servers from five to two, which means less to manage. He also has built in failover capabilities. "If we want all that, we need storage that multiple servers can access."

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