Can't open /dev/sdc1 exclusively. Mounted filesystem?

I was trying to reuse and old disk by adding to LVM. The error appeared when I tried to use pvcreate. I had already created the type 8e primary partition on the disk and rebooted, but still got the error.

The dm RAID system had claimed the device. I could see it on the list running dmsetup ls.

fedora-swap (253:0)
fedora-root (253:1)
fedora-home (253:2)
pdc_facghjcb (253:3)

After I removed the device from the raid manager, using dmsetup remove pdc_facghjcb pvcreate completed successfully, and I was able to add the drive to my LVM and format filesystems.