Can I connect two MacPros and a drobo pro with this switch
will both computers be able to see the drobo and use time machine to back up to the drobo?
two computer cannot access a drobo simultaneously.
One computer could access it and then share that access via a network (set up drobo as a shared directory/drive just like you would share a USB drive across a network).
To do it without a computer you’d need a Drobo Elite and access via iSCSI - or a Drobo FS.