[DRBD-user] use-bmbv restrictions?

[Kelly Byrd]

Reading this:

"     To get best performance out of DRBD on top of software raid (or any
other driver with a merge_bvec_fn() function) you might enable this
function, iff you know for sure that the merge_bvec_fn() function will
deliver the same results on all nodes of your cluster. I.e. the physical
disks of the software raid are of the exact same type. USE THIS OPTION ONLY
IF YOU KNOW WHAT YOU ARE DOING."

If I'm using a drbd on top of the md driver, it seems ok to turn on
'use-bmvm'. I currently have all identical drives underneath my raid0 md. I
am concerned about the last couple of sentences. Do the drives under md
really need to be identical?