Tapes written through a Brocade Encrypting Switch or DCX FS-18 Encrypting Blade need to be in DataFort Compatibility mode to write encrypted tapes that are readable by NetApp DataFort. When you go to configure your encryption target, you'll see a dropdown for "Desired Encryption Mode". Here you would select "DF-Compatible Encryption". Note that the default is "Native Encryption". BES encrypted tapes using this method will be readable and appendable to DataFort versions 2.2.x and 3.x and higher.
Yes, the tapes are compatible given the limitation of the DataFort tape header. AccordingFabric OS Encryption Administrators Gude v6.3.0 (53-1001341-02 August 7, 2009 published by Brocade):
Only DF version 2.x- and 3.x-compatible NetApp DataFort (DF) tape metaheaders and block formats
are supported for reading, decrypting, and decompressing the tapes.
Only DF version 2.x- and 3.x-compatible tape block formats and metaheaders are supported for
writing and encrypting tapes in DF-compatible format.
A DF-compatible license is required.
So the limitation is that the compatible DataFort tape metaheaders is a 2.x or 3.x revision. The 2.x and 3.x are the release levels that most DataFort tape encryption customers have used over the past 4 years.
The current DataFort FC-series supported OS release is 3.01. There is no announced 4.0 DataFort FC-series release candidate at this time. There may be a confusion with the E-series 4.x release which is currenlty deployed and supports Ethernet protocol encryption rather than fiber channel.