Running dd on ESX

Ever tried to run dd on ESX and failed?
Did you see this error ?

dd if=/dev/zero of=/vmfs/devices/disks/mpx.vmhba1:C0:T3:L0 bs=512 count=10
dd: can't open '/vmfs/devices/disks/mpx.vmhba1:C0:T3:L0': Function not implemented

Include "conv=notrunc" in your dd command and that should work for you.

dd if=/dev/zero of=/vmfs/devices/disks/mpx.vmhba1:C0:T3:L0 bs=512 count=10 conv=notrunc
10+0 records in
10+0 records out