Storage consolidation strategies for Microsoft Exchange

Posted on October 01, 2004

RssImageAltText

There are a number of storage options for small to medium-sized businesses (SMBs) to get a grip on burgeoning e-mail systems.

By Saqib Jang

The Microsoft Exchange user community is in the midst of a mass migration, providing an opportunity for customers to re-evaluate their server and storage architectures. For example, a SearchWin2000 survey revealed that 78% of Exchange 5.5 users would migrate to either Exchange 2000 or 2003 this year. Similarly, the META Group IT consulting firm estimates that about half of the more than 100 million Exchange users have migrated to Exchange 2000, with another 25% likely to move to Exchange 2000 or 2003 by year-end.

Typically, Exchange is one of the highest-capacity consumers in both large enterprises and small to medium-sized businesses (SMBs), with e-mail storage requirements growing anywhere from 50% to 300% annually.

This article covers a number of approaches to Exchange storage consolidation, with a focus on solutions that are feasible for SMBs.

Direct-attached storage

Until recently, direct-attached storage (DAS) was the only practical way to configure Exchange storage. In Exchange 5.5 and earlier versions there were limitations on the number of users per server, which made DAS the most practical configuration.

As e-mail storage requirements grow, the typical growth path is to add servers and DAS, which solves the storage capacity problem but likely exacerbates -operational and administrative problems and prohibits server/storage consolidation.

The benefits of a multi-server/DAS Exchange environment are that it is fairly inexpensive (depending on the hardware), Exchange administrators need little storage expertise, and it is relatively simple and quick to add more servers and storage, especially with Exchange 5.5 and earlier.

The disadvantages of a multi-server/DAS Exchange configuration are reduced storage utilization, slow backup/recovery times (which leads to "server crawl"), and decentralized server and storage administration.

Microsoft has made technical improvements in Exchange 2000 and 2003 that allow more users per server and better client performance over a wide area network, which enables a more centralized Exchange operation. Because of these upgrades, Microsoft often recommends a SAN infrastructure for customers that are deploying Exchange 2000 and 2003.

Microsoft has also enabled a NAS option for Exchange 2003 through a feature pack for Microsoft Windows Storage Server 2003. Microsoft also offers Virtual Disk Service (VDS) for multi-vendor management of SAN devices in Windows environments. VDS is included with Windows Server 2003 and Windows Storage Server 2003. With VDS, IT professionals have greater flexibility for making long-term investment decisions regarding SANs and other storage options.

The savings in resource utilization and improved backup performance enabled by SANs are well--understood. However, the acquisition and administration costs of Fibre Channel SANs have limited their adoption primarily to data centers in large enterprises. In addition, users have voiced concerns about Fibre Channel SANs typically requiring administrators to become storage experts in addition to their normal duties.

The storage networking industry has responded to these concerns with a new generation of affordable and manageable Fibre Channel SAN solutions that target SMBs and departments/workgroups within large enterprises.

"SANs not only address Exchange storage capacity issues, but also protect e-mail regardless of how much you have," says Tony Asaro, a senior analyst with the Enterprise Strategy Group consulting firm.

iSCSI SANs provide storage consolidation

iSCSI SANs, which use standard Ethernet-TCP/IP networks, are emerging as an alternative to Fibre Channel SANs (although iSCSI SANs can also be complementary to Fibre Channel SANs). iSCSI SANs allow end users to inexpensively reap the benefits of consolidated storage. The key benefit of iSCSI is that it -leverages existing IP knowledge and installed hardware and software.

iSCSI can significantly reduce acquisition costs versus DAS by enabling Exchange storage consolidation. In addition, it lowers the costs typically associated with business continuance and disaster-recovery solutions. iSCSI hardware is available from a wide variety of vendors. (For a complete list of iSCSI hardware vendors, see "What you need to build an iSCSI SAN," InfoStor, August 2004, p. 26.)

And products such as iSCSI disk arrays often come with easy-to-use management tools-sometimes for specific environments such as Exchange and SQL Server-as well as software for virtualization, snapshots, and replication.

Network Appliance supports iSCSI across its entire line of storage systems and recommends iSCSI for users that want to consolidate Exchange environments. "In the past, some customers viewed SANs as too complicated and expensive," says Rod Mathews, director of Windows marketing at Network Appliance. "Support of -iSCSI within Exchange 2003 makes setting up an Exchange storage consolidation infrastructure much easier."

"We used to spend an hour or two a day just trying to manage our DAS," says Stephen Greenlee, IT director at TRI-AD, a benefits administrator in Southern California. "Now that we've consolidated our storage into an EqualLogic iSCSI SAN, we spend virtually zero time on routine management tasks, giving us an opportunity to focus on applications and business processes." EqualLogic's PeerStorage Array 100E is a native iSCSI disk subsystem that is fully redundant and includes management software that makes it easy to set up and operate a SAN of any size.

Intransa's IP5000 iSCSI array makes scalability easier and more cost-effective because users can just add disk enclosures for more capacity rather than adding controllers as well. "The Intransa IP SAN fit right into our network and its capacity off-the-bat allowed us to consolidate eight servers down to four hosts attached," says Steve Walsh, CIO at Wildman Harrold, an international law firm. "Using the native IP infrastructure meant minimal training costs and learning curves for our administrators."

StoneFly Networks integrates IP SAN-based disk-to-disk backup and mirroring capabilities to offer a centralized solution for storage consolidation, provisioning, replication, and backup and recovery. According to Bob Boggan, vice president of sales and marketing at StoneFly, SMBs need simple, affordable, and automated storage consolidation, as well as backup and recovery. "StoneFly Backup Advantage gives SMBs and departmental workgroups 'push-button automation' to reduce manual intervention and alleviate IT resource constraints," says Boggan.

NAS has traditionally provided relatively low acquisition and maintenance costs. But Microsoft did not support NAS for Exchange until the release of Exchange 2003.

Windows Storage Server 2003 is Microsoft's platform for NAS, and it now accounts for about 50% of all NAS unit shipments. The Windows Storage Server 2003 feature pack allows storage of Exchange 2003 databases and logs on Windows Storage Server 2003 hardware. OEMs of Windows Storage Server 2003 include NAS vendors such as Dell, EMC, and Hewlett-Packard.

The Windows Storage Server 2003 feature pack provides the following four key management benefits:

  • Server consolidation-The feature pack allows Exchange and file-server storage to be consolidated onto inexpensive Windows Storage Server 2003 hardware.
  • Branch office deployments-Windows Storage Server 2003 offers low acquisition costs coupled with reliable performance and low operating and maintenance costs, critical requirements for Exchange storage in branch offices.
  • Business continuance-While traditional business continuance solutions often involve expensive replicated SANs, Windows Storage Server 2003 with the feature pack offers an alternative that provides business continuity features at a lower entry cost.
  • High availability-The feature pack enables Exchange cluster deployment without the expense of a SAN; two cluster nodes can share a Windows Storage Server 2003 NAS device to provide reliable shared storage for the cluster nodes.

"Windows Storage Server 2003 is a compelling platform for Exchange storage consolidation because of its low operating and management cost," says Marcus Schmidt, senior product manager, Microsoft Windows Storage Server 2003. "Because it scales above the terabyte range, a single Windows Storage Server 2003 server can easily support several Exchange servers."

The Hill School, a college preparatory boarding school in Pottstown, PA, is one site that is impressed with the Windows Storage Server 2003 feature pack capabilities: "The feature pack addressed our Exchange storage consolidation challenges," says Rick Bauer, The Hill School's CTO. "Deployment and management are easy, and it works seamlessly with our existing Exchange environment. We're now benefiting from better provisioning and improved security and business continuity."

Weighing tradeoffs

With the availability of a range of Exchange storage consolidation options, choosing the best solution requires a careful examination of the tradeoffs involved.

While the acquisition cost and manageability of Fibre Channel SANs have improved significantly, organizations should carefully evaluate the degree of expertise required to support Fibre Channel technology.

Microsoft's release last year of an iSCSI initiator spurred a rash of iSCSI product introductions. In fact, more than 50 vendors have qualified their iSCSI products under Microsoft's Designed For Windows Logo program. However, iSCSI is relatively unseasoned compared to Fibre Channel SANs and NAS.

While iSCSI promises significantly lower infrastructure acquisition and management costs, users have to carefully evaluate the reliability and performance of iSCSI SANs due to the relative immaturity of the technology. Users should obtain reference site information and evaluate interoperability and performance test data before taking the iSCSI plunge.

Compared to iSCSI SANs, Windows-based NAS is highly interoperable and mature, with plug-and-play installation and low up-front installation and on-going maintenance costs. Windows Storage Server 2003 delivers a solution that, for SMBs especially, could make Exchange storage easier to deploy and manage than IP- or Fibre Channel-based SANs, and overall provides better scalability than DAS.

SMBs with 100 to 1,500 users and multiple servers providing file, print, Web, and Exchange services will likely have the most to gain from consolidating Exchange and other storage on Windows Storage Server 2003. For example, it is typical to see four or five servers' worth of Exchange 5.5 mailboxes (with an average count of 150 to 400 mailboxes) consolidated onto a clustered pair of Exchange 2003 servers, which provides better reliability, superior performance, and lower total cost of ownership.

Saqib Jang is founder and principal at Margalla Communications, a Woodside, CA-based strategic and technical marketing consulting firm focused on storage networking. He can be contacted at saqibj@margallacomm.com.


Comment and Contribute
(Maximum characters: 1200). You have
characters left.