Changing the value of data_directory

I'm not sure how they done it but our Platforms Team seem to have installed PostgreSQL 9.4.1 in both

/var/lib/pgsql/data

Which is want I want

And

/var/lib/pgsql/9.4/data/

Which is want I don't want!

For most of our clusters we get:

postgres=# SHOW data_directory;
data_directory
---------------------
/var/lib/pgsql/data
(1 row)

postgres=#

but for a couple we get:

postgres=# SHOW data_directory;
data_directory
---------------------
/var/lib/pgsql/9.4/data
(1 row)

postgres=#

My questions are:

1. How/when is the value of data_directory set - is it set as part of the install?

2. Is it possible to change the value of data_directory without doing a frest install?

Thanks

Austen

Austen Birchall  Senior Database Administrator
Met Office