SCSI + HD tach=question

[overclockedpc]

This is my first SCSI drive, so I'm curious if these results look normal. The only thing I'm concerned about is the dips across the graph. Please let me know.

BTW, this is a seagate drive (manufactured for HP) - 72.8GB 15k U320 with a Adaptec 29160N U160 adapter and, in case it matter, a 2 device LVD/SE cable with built-in terminator.

 

[overclockedpc]

Oh, and this........

 

[GotNoRice]

The only thing I'm concerned about is the dips across the graph.

I might be totally off on this, but from my experience the dips are caused from other disk access while the test is running. If I run HDtach right off a fresh boot with AV disabled, etc it will come out clean but if I do it while I have my normal bunch of programs going in the background it will show small dips like that. This is the case on several machines I have.