I'm still have no clue about this issue

The LTO2 max theoretical speed is about 40MB/s, right?
What speeds are you guys getting with a similar setup?

I'm getting about 2MB/s

I'm trying to ajust the said cache on the adaptec controler. have been looking for module options, etc so far no solutions

I'm tempted to try to boot with a liveCD to override dss, but I wanted to fix the problem within dss. Any more tips

Thanks