Planning for Microsoft® Exchange Server 2007 Deployments on the Hitachi Adaptable Modular Storage 2000 Family - Reference Architecture and Best Practices Guide is a technical whitepaper from Hitachi.
"The guide is intended for Exchange and storage administrators and IT managers concerned with the deployment of scalable, affordable and highly available storage solutions for Microsoft Exchange 2007.
Multiple factors influence Exchange Server 2007 performance and availability, leading to interactions that can constrain service levels. At the extreme, with improper planning, these interactions can significantly affect an organization’s overall business goals. This guide describes a variety of Exchange Server 2007 storage related topics and introduces methods for incorporating them into a successful overall architecture and subsequent implementation.
The solutions described in this guide are based on testing performed using both Windows Server 2003 and Windows Server 2008 as the base operating system and using Exchange Server 2007 Service Pack 1. This guide provides a consolidated view of the information required to make optimal choices when designing a storage infrastructure for Exchange Server 2007."
You may also be interested in this one: Planning for Microsoft® Exchange Server 2007 Deployments on Hitachi Adaptable Modular Storage 1000 - Solution Deployment Guide.
The good thing about these whitepapers is that they cover the general guidelines for planning and sizing an Exchange Server 2007, so they go way beyond a dedicated storage guide. Read them and you won't regret it!