Don't put your mdf and ldf in the root of your cluster drives
Colin has just blogged about a nasty error that occurs
if you have your data and/or log files in the root of a cluster drive and you
dettach the database.
Read Colin's blog post for more details http://sqlblogcasts.com/blogs/grumpyolddba/archive/2010/02/01/detach-a-database-and-take-out-a-cluster.aspx