A coworker was asking about caching and LUN sizing practices for a Windows disk served on VNX storage. Here is a list of best practices for Windows LUNs, with a couple special notes for Exchange.
User Storage System RAID - This seems like a no-brainer, but I often see people utilizing host-based RAID (particularly software RAID) on virtual machines to stripe across two or more VMDKs to get logical disks larger than 2TB. This can have a substantial impact on CPU utilization. You paid for that expensive storage appliance, so use it!
Use Basic Disks in Windows - This reduces CPU overhead on the host. If you don't have a reason to use dynamic disks, don't do it! Your storage appliance can take care of growing or shrinking the LUN, so this eliminates the most common reasoning I hear for dynamic disks.
Use the Default 8KB Cache Page Size - This is ideal for a typical Windows environment.
Use the Default 64KB Element Size - Again, the default configuration is ideal for most Windows boxes.
Align the LUN with a 1,024KB Boundary - LUN alignment is a big deal, particularly with heavy-IO hosts. Use a utility like DiskPart to accomplish this.
Choose the Correct Page Size for Exchange - A 4KB page size is ideal for Exchange servers up to 2003. With Exchange 2007, choose an 8KB page size. For Exchange 2010, this doubles again to a 16KB page size.
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