Hi, Our current Exchange 2007 environment consists of 2 x Mailbox Servers (SAN Boot, SAN Exchange Storage) & 1 x HUB / CAS server (SAN Boot & SAN Storage). We are experiencing performance issues for users on one of the mailbox server that hosts a disproportionate number of mailboxes (2.5 TB v 0.75 TB on the second server). Our plan is to stand up 3 new mailbox servers (the user base is due to expand in the near future) and disperse the mailboxes across the servers in a more proportional manner. I'm now considering my options for designing the storage groups for the new mailbox servers. Traditionally I would gather performance counters from the current infrastructure (number of emails sent/received, average message size and mailbox quota limits) and would run these figures through the Exchange Calculator. From here I would work out how many mailboxes could be hosted on a 150GB LUN and design the layout as such. My question is whether this is the best approach? Is there a better approach to follow? Any advice would be appreciated! Thanks in advance. Andrew

Recommendation is, keep on database in one storage group. What kind of performance issue you are facing?Gulab Prasad, MCITP: Exchange Server 2010 | MCITP: Exchange Server 2007 MCITP: Lync Server 2010 | MCITP: Windows Server 2008 My Blog | Z-Hire Employee Provisioning App

Hi Andrew, About how to caluate the mailbox server for your requirement, you could refer to below: http://blogs.technet.com/b/exchange/archive/2009/11/09/exchange-2010-mailbox-server-role-requirements-calculator.aspx Regards!Gavin TechNet Community Support