iostat -x | grep VxVM

The output of this shows VxVMnnnnn where nnnnn corresponds to the minor device number of the block device.

Using nnnnn with a find command will tells us the block device…

find /dev/vx/dsk -type b -exec ls {} \; | awk '{print " ",$6,$10}'" | grep " nnnnn "

Display in megabytes per second only active devices and retain the header with…

iostat -mxz 1 | egrep "Device:|VxVM"