Partitioning a disk into multiple logical drives is pointless for SQL. You may as well leave it as one large drive and put everything on it.
Multiple disks gives you multiple spindles (reading/writing in parallel) and, depending how it's set up (RAID) less risk of complete failure. With partitions on a single disk you have one spindle and if the drive fails everything's gone.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
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