I justed posted my new server build in compulsive design thread .

I pre cleared five 3TB drives simultaneously this week. The pre clear speeds were 120-130 Mb/sec at the beginning and towards the end of the drives they were around 70 Mb/s with five drives being pre cleared simultaneously. I just wanted to see if these speeds are what should be expected. I haven't started transferring the data to the tower yet.

 

Thanks

Mani

Your speeds are very respectable and exactly where they should be.  The difference from start to finish is cause by the different amount of data on different parts of the disk.  The outer tracks are longer, so they can squeeze more data on to them, and since the disk rotates at a constant speed, they result in higher transfer speeds.