The most recent RHEL/CentOS 6.x operating systems' device-mapper package (device-mapper-1.02.79-8.el6.* and newer) cause the following error, while partition mappings are removed with kpartx:
device-mapper: remove ioctl on <DEVICE> failed: Device or resource busy
To fix it manually, please commend the following lines in the /lib/udev/rules.d/13-dm-disk.rules on each affected HV and BK server of the OnApp cloud:
# egrep -e '="[dm_]*watch"' /lib/udev/rules.d/13-dm-disk.rules
Service restart is not required after making changes.