http://www.sturge.ca/?p=108

http://www.overclockers.com/forums/showthread.php?t=667317

When preparing a disk or partition for use on Linux, you may see an error such as:

/dev/sda1 is apparently in use by the system; will not make a filesystem here!

1. Check if the filesystem is already mounted

   • mount

   • cat /etc/mtab

2. Check if LVM is involved

   • pvs

   • vgs

   • lvs

3. Check if Linux software RAID is involved

   • dmsetup status

   • dmsetup ls

   • dmsetup remove xxxxxxxx