dd command to backup sd card doesn't work

[huchord]

Need to back up sd card, which is disk mpx.vmhba32:C0:T0:L0

cd into a datastore and run this command:

[root@localhost:/vmfs/volumes/556c6cc9-7b6835f6-d569-ac162da1c290] dd if=/dev/disks/mpx.vmhba32:C0:T0:L0 of=./sdBackup.img conv=notrunc

dd: /dev/disks/mpx.vmhba32:C0:T0:L0: Function not implemented

Looking for some ideas.

[continuum]

I would have assumed that that command would work.

Other than that I also have a hard time predicting which dd commands are working and which are "not implemented"