> Did you run vmstat, top or similar while this was happening? What did
> the user/system/idle time and interrupt rate look like?
to be honest no, because the system was that slow that it was difficult
enough to kill newfs, but I hope can repeat that this weekend without
disturbing the users.
How can I check the interrupt rate?
> 
> The 3ware controller needs all transfers aligned on a 512-byte boundary.
> That's OK for usual file system access since all the transfers are
> aligned naturally. newfs accesses the raw device so the transfers go
> directly from the card to user memory, and the buffer can be unaligned.

Do I understand you right that the performance problem might be a newfs only
problem? 

> 
It would be good to see the numbers
> to make sure that is what's happening though.
I try to organize access to the server for the weekend, to get this numbers.

Thank you very much!

Arne