Delphix supports TectiaSSH v6.4.2, as it establishes a connection to Source and Target Host machines from the Delphix Engine. Earlier versions of TectiaSSH may not be compatible due to a known TectiaSSH bug.
Version v6.3.8 build 79 behaves slightly differently from the latest TectiaSSH Version, v6.4.2, which is compatible with the Delphix Engine ssh requirements. Stack traces, in version 6.3.8 build 79, show that there are periods of "hangs"; during this time, the Delphix Engine ends up waiting on the remote environment to close the ssh connection- since the remote environment never does close it's stdin/stdout/stderr the Delphix Engine ends up waiting for the ssh connection to go away. The issue was discovered when the Delphix Engine closed the file descriptors but was still waiting for the ssh session to exit. When the session never closed, it forced the Delphix Engine to sit and wait in a deadlock until the job timed out and was marked failed.
This is a known issue in the Tectia software and is fixed by upgrading to v6.4.2.