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Exchange 2010 archiving could significantly increase SAN expense

Exchange 2010's new archiving features can save money on storage when used with direct attached storage or JBODs, but gets a lot more costly when stored on a SAN.

Microsoft Corp. has taken steps with Exchange 2010 to make it less expensive to store Exchange data emails, even in high availability (HA) configurations. But experts say the cost really depends on what type of hardware setup you require for your email archives.

The changes Microsoft made to Exchange were designed mainly for it to be run on cheaper JBODs or direct attached storage, yet many organizations would prefer or find it more efficient to use their storage area networks (SANs). And that can make Exchange 2010 quite costly to run.

David Ferris, senior analyst of Ferris Research, ran down the costs of Exchange 2010 with a SAN on a blog post on his company's website last month.

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"Eighteen terabytes (TB) of NetApp Fibre Channel SAN costs about $240,000 when switches, controllers, shelves, and software are included," Ferris wrote. "After allowing for snapshots, this gives perhaps 12 TB of usable storage, which translates to $20 per gigabyte (GB). Most customers run Exchange 2010 in RAID 10, which doubles the cost. Furthermore, many customers have redundant sites to provide for better recoverability. So, total SAN costs often reach an exorbitant $80 per GB."

In Exchange 2010, the email archive is part of the main message store. "It uses quite a lot more storage," Ferris said in an interview with "You are now going to be putting your archives into a sort of secondary archive mailbox, and you are going to put PST files in the archive. So, you'll find that you are storing five to 10 gigabytes per user. If you are using SAN storage, then that is quite a lot of money."

He added that many Exchange users have complained about the cost of SAN storage, and that Microsoft has made changes specifically to facilitate the use of cheap storage. "Modern [JBOD] storage is really cheap," said Ferris. "You can get a terabyte of storage for between $50 and $100. It doesn't have all the performance characteristics of SAN storage, but it's attractive to be able to use some of that sort of storage."

Microsoft has made changes to Exchange over the past few years to address these user demands. "[Microsoft] went back and looked at the database structures and optimized everything for IO," said Paul Sebben, vice president of consultant Preeminent Solutions, a Microsoft Gold Partner. "They looked at database internals and how data was read and written and optimized IO to the disk. They introduced some of the concepts in 2007 and further refined them in 2010."

Sebben said the emphasis on JBODs actually started with Exchange 2007. "In 2007 they introduced the concept of multiple databases with continuous cluster replication," he said. "Microsoft recommends that if you have three or more copies of your database replicated around your environment, you don't need to use RAID storage. That really reduces cost. When you have three copies of your database replicated, you don't need a high availability solution like a SAN. If you lose a server, you can failover to one of the other copies."

SAN or not?

J. Peter Bruzzese, an independent Exchange Server consultant, says it's a waste of money to put an email archive on high-performance storage.

"Every server typically has storage, right?," Bruzzese said. "Let's say you have a SAN that you paid $50,000 for, and then you have a server that's running Exchange and Hyper-V, and you've got hardware RAID set up inside of it, and redundant power supplies off the server. You've got some pretty impressive storage. It's just not SAN storage. Why not use that for archiving?"

Still, many storage managers tend to take a conservative approach and may be resistant to use cheaper JBOD storage. If they've already gone to a SAN, they'd rather not manage their Exchange archive outside of that SAN.

"There's a lot of inertia behind SAN storage," said Ferris. "Your support people are used to it, you've got systems and procedures in place to fix things if they go wrong. If you've committed to SAN technology, it's not something you dump overnight. So, if you are upgrading to Exchange 2010, you are probably going to have to spend a lot more money on SAN storage to provide for the needs of Exchange 2010."

Another option is to use a third-party email archiving tool. These applications were initially designed to free up space on production servers and speed up backup times, but Ferris said they are substantially cheaper than using Exchange 2010's archiving with SAN storage.

Another reason organizations might be hesitant to use Exchange's 2010 archiving feature is that it's not designed with e-discovery or compliance in mind. "If you are talking about real legal archiving, in the sense of being in harmony with regulations, this is not the ultimate solution," Bruzzese said. "This is an archive feature for mailboxes, it's not the best e-discovery feature. If you have a big-time legal requirement, then yeah, third-party."

"However, when it comes to what this tool is for, archiving mailbox data, I think it can take the place of managed folders. Messaging Records Management, or MRM, is hard to configure. This could be an easier alternative to setting up MRM for some admins."


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