Due to the extension requests problem when file domains are the master domains in a storage pool (bug 1083476) and the fact that the fix is only introduced in 3.4, mixing domain of different subtypes (block/file) should be prevented in compatibility versions lower than 3.4
There are too many issues with mixing block and file domain (e.g. bug 1083476, bug 1082941). Let's block this for 3.4 too, and enable it in 3.4.1/3.5, once we have a working solution.
Following Allon's comment, since all relevant issues with mixed domains were solved in 3.4, we decided to enable mixed domains from version 3.4 up and including.
3.3 shared blocked 3.4 shared works verified using av7
Closing as part of 3.4.0