A few months Bruce Langworthy wrote an excellent article regarding some new recommendations for setting the Windows Disk Timeout value - http://blogs.msdn.com/b/san/archive/2011/08/15/the-windows-disk-timeout-value-understanding-why-this-should-be-set-to-a-small-value.aspx.
This post got me thinking about Exchange and how we deal with I/O problems. If you haven't read Bruce’s article, it explains that the default disk timeout of 60 seconds means that Windows will not report the hung I/O for 60 seconds and won’t retry the I/O for 8 minutes. 8 minutes is far too long to wait before retrying a hung IO, so Microsoft is releasing new guidance recommending changing the Windows Disk Timeout setting to a value that aligns with your storage architecture.
The question in my mind for Exchange was simple, how does this disk timeout behavior affect Exchange DAG deployments; more specifically should I reduce the Windows Disk Timeout on my Exchange Servers as per the new recommendations or leave things alone??
To answer this question I approached some of our ESE developers to get their thoughts… this is what came from that discussion…
I decided that before we could determine what to do with our disk timeout settings that first we must understand what intelligence Exchange Server 2010 SP1 introduced and how it might interact with disk timeouts.
Read the complete blog at http://blogs.technet.com/b/exchange/archive/2011/11/17/windows-disk-timeouts-and-exchange-server-2010.aspx
Read my favorites blogs:
Designing a backup less Exchange 2010 Architecture
Step by step guide for upgrading Active Directory from Microsoft Windows 2003 to Microsoft Windows Server 2008
Microsoft Exchange 2010 CAS Array – Steps and Recommendations
Appear Offline in Microsoft Office Communicator Server 2007
Microsoft Exchange 2010 Test cases
Microsoft Exchange Server 2010 Disaster Recovery