I recently ran HD Tach on my drives and was surprised at the poor results. 1 HP Smart Array 6400 controller (2 Channels) C:/D: 2x300GB 10,000 RPM (3.5) RAID 1, Channel 1 E:/F: 4x146GB 10,000 RPM (3.5) RAID 1+0, 2 drives on Channel 1 and 2 drives on Channel 2 The C/D drive goes from 75 to 40 MB/s as reads progress across the disk. This is great. Makes sense for a 2 drive mirror. The E/F drive starts at 115 MB/s, holds at that rate till the 235GB point, then starts declining to 80MB/s at the end of the drive. This does not seem right. All 6 drives are Ultra320. It seems like there is a bottleneck limiting the peak performance of the E/F combination. I was thinking the system bus, but it's a 64-bit PCI-X, which should be able to handle the throughput. Any ideas? Anything I can check in the HP managment tools? This has been bugging me for days.