How do I see disk usage within a Fusion Drive (CoreStorage Logical Volume)?

I just created a "Fusion Drive" on my MacBook Pro by following "How to make a Custom CoreStorage Drive in OS X".

It was created with a 256GB SSD and 320GB HD, with the SSD set as the "primary" disk in the logical volume. However, I'm not seeing much of a speed increase, and I'm not sure my data is being stored to the SSD.

How do I confirm that most of my data is stored on the SSD within a Logical Volume?

I was hoping I could simply see disk usage for each disk within the logical volume, but it looks like diskutil cs list doesn't report that.

iostat command check out the complete article from JollyJinx blog.

http://jollyjinx.tumblr.com/post/34638496292/fusion-drive-on-older-macs-yes-since-apple-has