I am in the process of configuring a new SAN for a SQL Server. I am going to use RAID 10 for all raid groups. I have enough drives to do the following: Tempdb - 4 drive Raid 10 Logs - 4 drive Raid 10 Data â€“ 12 drive Raid 10 (will contain the following files: primary data file â€“ 46% of all of the IO on server secondary file that contains all of the indexes â€“ 33% of all of the IO on server) I can create a Raid Group (raid 10) with 12 disks that has just one LUN on it. This would contain the data file and the index file. Advantage â€“ many spindles handling the IO of two heavily used SQL files. Disadvantage â€“ Data file (46% of total IO) on server and Index file (33% of total IO) on server will be competing for the same resources. My other choice is to use 8 disks for one Raid Group (raid 10) that has one LUN on it. The data file would go here. The other 4 disks would be another Raid Group (raid 10) that has one LUN on it that contains the Index file. Advantage â€“ The IO for two heavy utilized SQL files would separate. Disadvantage â€“ Less spindles dedicated to each Raid Group. I appreciate your input.