Disk Filling up with /var/lib/ureadahead/debugfs

Environment: Ubuntu Server 10.04

Hi,

While I was looking at df-h

I notice this

none 23G 14G 7.6G 65% /var/lib/ureadahead/debugfs

I tried ls, see nothing, tried vi the "debugfs" noting much too except a few description lines.

1) Is this important?
2) How do I delete it?
3) If it is not importing, How do turn it off?

Please help!

Thanks.

Regards / Joseph