Curt Sampson writes:

> This would still display the same problems WRT even numbers of
> _interleave_, since nothing's changed as far as which disk it's
> going to hit for a particular block on the ccd.
> 
> I expect the asymmetry is happening because the inode blocks end
> up concentrated on one disk when a power-of-two interleave is used.
> This might affect even small interleaves, because I'd bet that ffs
> uses the inodes in a cylinder group in order from the beginning.
> 
> It'd be nice to have a detailed analysis of just what changes you
> can expect to see on a ccd given different interleaves.

It'd be great if it were possible to gather a record of all disk IO
operations, then simulations on real data could be run, and any such
effects would presumably be simpler to diagnose.