Thanks for your reply, but I don’t think your experience applies to my case.
I’m running a late 2013 iMac with Mac OS X 10.10.1 (Yosemite)
I [wrongfully] assumed the phrase “Time Machine” would qualify my query sufficiently.
While I have full disk encryption enabled on my main drive, my Drobo is network attached with dedicated shares designated for Time Machine use on two computers.
When connecting the share to the Time Machine software, I designated “encrypted backups” which produces an (Mac HFS) encrypted sparsebundle to contain the subsequent backups.
I’ve been monitoring the process closely and so far have encountered no problems creating, viewing, or restoring from the resultant backups.
hi tom, thats fair enough,
from what you describe, it seems like your drobo is storing your data within its volume, and that the data /content itself just happens to be encrypted, in which case it should be ok, but lets wait for some mac experts with more knowledge indeed