I have a SAN with a RAID 10 (16 Drives) and a stripe size of 512. I want to align the disks for better SQL Server performance, the problem is that the OS is already installed on a non-aligned drive and SQL Server is running in production using non-aligned drives. My current 8 drives starting partition offset is 32256 and the file allocation unit size is 4096. IOPS = 750 MB/sec = 13 Latency = 10ms Disk Queue Length = 7 Block Size = 20KB 1.Can I just align the disks where the SQL Server database files live? 2.Aligning only the drives where the SQL Server database files live would that create a bigger block size in IOPS? 3.Do I have to also align the drive where the OS lives? 4.Maybe the main question is what controls the block size that gets sent to the SAN?