Sun wrote the CDDL to be intentionally incompatible with the GPL, and a lot of the motivation for that came directly from engineers working on Solaris who were

Sun wrote the CDDL to be intentionally incompatible with the GPL, and a lot of the motivation for that came directly from engineers working on Solaris who were opposed to their work being copylefted. btrfs is awesome and stands to completely eclipse ZFS -- but don't pretend for a second that it ain't provincial. It's designed directly for Linux's powerful VFS layer and would be a bitch to port elsewhere.