For best performance on Microsoft Windows 2003 (SP1 or better) on an EMC Clariion SAN, make sure the disk alignment of the LUNs is correct. I found the information on the following sites, including some performance testing and some diagrams in case someone is interested. This is mostly being documented for future reference.Performance Tests
Clariion blogs: Disk Alignment
If you have Microsoft Windows 2008, you do not need to worry about this, disk alignment is done properly by the O/S without any intervention from the user.Once the LUNs have been presented to the host, follow these steps.
- Open command prompt and run DISKPART
- From DISKPART, select the LUN/Disk that you want to align with the command SELECT DISK 1. Make sure you select the correct disk. To view a list of available disks, run the command LIST DISK.
- Once the disk has been selected, run the following command: CREATE PARTITION PRIMARY ALIGN=32. This will correctly set the alignment on your drives.
- You can now exit the DISKPART utility and format the disk from the Disk Management interface in Windows.