I’ve a Drobo 5N with 5 3TB disks in it.
I use OS X and want to create a large (2TB ish) encrypted disk image on the drobo.
OS X would see it was a drive with files on it, the Drobo would see it as a single 2TB file.
Is this safe? Does the drobo play nicely with such files? Is there any other recommended way to store encrypted files on the drobo?
By definition it should work.
The 5N supports file sizes up to 16TB (yes, single file - see ext4 specs).
SMB/AFP is capable to stream these files correctly.
Still, from my personal experience I know that streaming large disk images over the network can be painfull in therms of security - not only with a Drobo. If one of the nodes, your Mac for example, “dies” during access a corruption can occur.
If this is not your only backup it’s definitly a good way to store a encrypted backup on a Drobo 5N.