Exchange 2010 SAN Costs Are Significant

In December, we published a bulletin titled Cost of Exchange 2010 Storage Not An Issue. This said that storage is now so cheap that Exchange 2010 users needn’t worry about storage costs.

We still subscribe largely to that view. However, it’s not true for organizations that are committed to storage area networks (SANs). Here is a more detailed analysis.

SANs are used in many Exchange environments. They are expensive, however, so many Exchange users prefer to offload rarely accessed and archived material to less expensive storage.

For example, 18 terabytes (TB) of NetApp Fibre Channel SAN costs about $240,000 when switches, controllers, shelves, and software are included. 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.

With Exchange 2010, the archive is part of the main message store. Additionally, message stores now contain a lot of material formerly stored in Personal Storage Table (PST) files. If SANs are used, the cost of the additional storage is crippling: An extra 5 GB per user translates to $400 per user!

Exchange 2010 responds to the problem by supporting more modern, inexpensive storage. This also reduces message store I/O by some 90%, since Exchange 2003 provides for slower disk speeds. Modern non-SAN storage costs are about $0.30 per GB, including RAID 10 and redundant servers.

Microsoft hopes that the new drive technology will thus resolve the storage cost problem. It will be useful in many cases, but it is not a panacea. Many organizations have a sunk investment in SANs for a number of applications. These organizations will be resistant to using a separate set of technologies, with separate management tools, for the special case of email.

Thus, for Exchange users who have invested in SANs and are committed to the technology, storage cost is an issue for all versions of Exchange, including Exchange 2010. For SAN users, third-party archiving tools will continue to be an attractive way of allowing live mailboxes to live on SANs while archives reside on less expensive media.

David Ferris, with particular thanks to Alan Elliot and Kevin Hood of Mirapoint, for educating me on the real costs

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  1. […] reject this notion due to storage cost as the primary reason. Rightfully so if you are leveraging SANs (little dated but cost haven't come down that significant) but Microsoft has designed Exchange […]

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