Are we able to move an internal log to external log on an existing
filesystem? (xfs_growfs has an option for it "-x", but the man page says
it is "not implemented") - If this is not implemented, do we have
alternative measures for creating an external log on an existing
filesystem?
Its not implemented. It would be quite straightforward to do
offline (I remember Steve sent mail about an unsupported way to
do this a few years ago) - could be done through xfs_db. It's
really not a difficult extension to xfs_db if you want to try
coding it.
Online would be more involved, though could be done (probably
via xfs_freeze, then xfs_growfs-x+<new code>, then thaw).